# Patent

## Title
Remote storage disk control device and method for controlling the same

## Abstract

A storage device system includes an information processing device, a first storage device equipped with a first storage volume, and a second storage device equipped with a second storage volume. The information processing device and the first storage device are communicatively connected to one another. Also, the first storage device and the second storage device are communicatively connected to one another. The information processing device is equipped with a first write request section that requests to write data in the first storage device according to a first communications protocol, and a second write request section that requests to write data in the second storage device according to a second communications protocol. The information processing device creates first data including a first instruction to be executed in the second storage device.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for controlling a storage device system, a storage device system, and a storage device.
2. Related Background Art
Disaster recovery in information processing systems is attracting attention. As a technology to realize such disaster recovery, a technology in which a copy of data stored in a storage device that is installed in a primary site is also managed by a storage device that is installed in a remote site located away from the primary site is known. By using the data stored in the storage device installed at the remote site when the primary site is hit by a disaster, processings that are performed at the primary site can be continued at the remote site.
For data transfer from the primary site to the remote site, a method in which data is exchanged between an information processing device at the primary site and an information processing device at the remote site is known. The information processing device at the primary site transfers a copy of data that is written in the storage device at the primary site to the information processing device at the remote site. The information processing device at the remote site that has received the copy of data sends a request to write the data in the storage device at the remote site.
When data is stored as a backup by the method described above, a substantially large amount of data flow occurs on the network between the information processing devices. This causes a variety of problems such as an increased interface processing load on the information processing devices, delays in other data transmissions to be conducted between the information processing devices, and the like. Also, the method described above needs software to control data backup to be installed in each of the information processing devices. For this reason, management works such as upgrading the software and the like need to be performed on all of the information processing devices that execute data backup processings, which increases the management cost.
SUMMARY OF THE INVENTION
The present invention has been made in view of the problems described above, and relates to a storage device system, a storage device and a method for controlling a storage device system.
In accordance with an embodiment of the present invention, there is provided a method for controlling a storage device system that includes: at least one information processing device, a first storage device equipped with a first storage volume, and a second storage device equipped with a second storage volume, wherein the information processing device and the first storage device are communicatively connected to one another, the first storage device and the second storage device are communicatively connected to one another, the information processing device is equipped with a first write request section that requests to write data in the first storage device according to a first communications protocol, and the first storage device is equipped with a second write request section that requests to write data in the second storage device according to a second communications protocol. The method comprises: a step in which the information processing device sets a first instruction to be executed at the second storage device as first data; a step in which the information processing device sends a request to write the first data in the first storage volume to the first write request section; a step in which, when the first data written in the first storage volume is an instruction to the second storage device, the first storage device sends a request to write the first data in the second storage volume to the second write request section; and a step in which the second storage device executes the first instruction that is set as the first data written in the second storage volume.
It is noted that the information processing device may be, for example, a personal computer, a work station or a mainframe computer. The storage device may be, for example, a disk array device or a semiconductor storage device. The storage volume may be a storage resource that includes a physical volume that is a physical storage region provided by a disk drive, and a logical volume that is a storage region logically set on the physical volume. Also, the communications protocol may be, for example, a WRITE command stipulated by a SCSI (Small Computer System Interface) standard. As a result, without adding new commands to the operating system, the information processing device can make the second storage device to execute the first command.
Here, for example, when the first command is a command to read data of the first storage device, the second storage device can have a copy of the data of the first storage device according to an instruction from the information processing device. Therefore the present method can reduce the amount of data communicated between the information processing devices in the data backup management. Also, software for controlling data backup does not have to be installed on all of the information processing devices that are performing data backup, which lowers the management costs.
Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, various features of embodiments of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically shows a system configuration of an information processing system in accordance with an embodiment of the present invention.
FIG. 2 schematically shows a structure of a disk array device in accordance with an embodiment of the present invention.
FIG. 3 shows a LUN map information table in accordance with an embodiment of the present invention.
FIG. 4 schematically shows a diagram illustrating a data writing operation using virtual volumes in accordance with an embodiment of the present invention.
FIG. 5 shows a command device management table in accordance with an embodiment of the present invention.
FIG. 6 shows a command device interface in accordance with an embodiment of the present invention.
FIG. 7 is a schematic diagram illustrating execution of commands set at command devices in accordance with an embodiment of the present invention.
FIG. 8 shows a flowchart of an operation to control a command device in an information processing device in accordance with an embodiment of the present invention.
FIG. 9 shows a flowchart of an operation to control a command device in a storage device in accordance with an embodiment of the present invention.
FIG. 10 shows a pair management table in accordance with an embodiment of the present invention.
FIG. 11 shows a schematic diagram illustrating a pair forming processing in accordance with an embodiment of the present invention.
FIG. 12 shows a relation between a primary volume and a primary journal in accordance with an embodiment of the present invention.
FIG. 13 is a schematic diagram illustrating a journal acquisition processing in accordance with an embodiment of the present invention.
FIG. 14 is a schematic diagram illustrating a restoration processing in accordance with an embodiment of the present invention.
FIG. 15 shows journal data regions of a primary journal and an auxiliary journal in accordance with an embodiment of the present invention.
FIG. 16 shows a flowchart of a journal acquisition processing and a restore processing performed in information processing devices in accordance with an embodiment of the present invention.
FIG. 17 is a schematic diagram illustrating a swap processing in accordance with an embodiment of the present invention.
FIG. 18 is a schematic diagram illustrating a state in which the swap processing of the present embodiment is completed.
FIG. 19 shows a flowchart of a swap processing in a second information processing device in accordance with an embodiment of the present invention.
FIG. 20 shows a flowchart of a swap processing in a first storage device in accordance with an embodiment of the present invention.
FIG. 21 shows a flow chart of a swap processing in a second storage device in accordance with an embodiment of the present invention.



PREFERRED EMBODIMENTS OF THE INVENTION
[Example of Overall Structure]
FIG. 1 schematically shows an overall structure of an information processing system including a storage device system in accordance with an embodiment of the present invention. The information processing system of the present embodiment includes an information processing device 11, and at least a first storage device 10 and a second storage device 20. The first storage device 10 is equipped with a logical volume(s) 30 on which the first storage device performs data input/output processings (hereafter referred to as a “first logical volume(s)”), and the second storage device 20 is equipped with a logical volume(s) 40 on which the second storage device performs data input/output processings (hereafter referred to as a “second logical volume(s)”).
The information processing device 11 and the first storage device 10 are communicatively connected to each other via a first network 50. The first network 50 may be, for example, a LAN (Local Area Network), a SAN (Storage Area Network), an ISCSI (Internet Small Computer System Interface), an ESCON (Enterprise Systems Connection)®, or a FICON (Fibre Connection)®.
The first storage device 10 and the second storage device 20 are communicatively connected to each other via a second network 60. The second network 60 may be, for example, a Gigabit Ether Net®, an ATM (Asynchronous Transfer Mode), or a public telephone line.
[Information Processing Device]
The information processing device 11 may be a computer that is equipped with a CPU (Central Processing Unit), memories, and other devices. The information processing device 11 may be a personal computer, a work station or a mainframe computer. The information processing device 11 may be composed of a plurality of computers that are mutually connected. An operating system is operating on the information processing device 11, and application software is operating on the operating system.
[Storage Device]
FIG. 2 shows a structure of a disk array device, which is described as an example of the first storage device 10 and the second 20. Instead to of the disk array device, the first and second storage devices 10 and 20 may be any appropriate devices, such as, for example, semiconductor storage devices. For example, the disk array device 10 is equipped with various components including a channel control section 201, a remote communications interface 202, disk control sections 203, a shared memory 204, a cache memory 205, a switching control section 206 that is composed of cross bus switches that communicatively connect the components described above, a management terminal 207, and memory devices 208. The first and second storage devices 10 and 20 may have the same structure.
The cache memory 205 is used to temporarily store data that is exchanged mainly between the channel control section 201 and the disk control sections 203. For example, when a data input/output command which the channel control section 201 receives from the information processing device 11 is a write command, the channel control section 201 writes in the cache memory 205 write data received from the information processing device 11. Also, an appropriate one of the disk control devices 203 reads the data written in the cache memory 205, and writes the same in the memory devices 208.
The disk control section 203 reads a data I/O request stored in the shared memory 204 written by the channel control section 201, and executes data writing processing or data reading processing with respect to the memory devices 208 according to a command set at the data I/O request (for example, a command according to a SCSI standard). The disk control section 203 writes in the cache memory 205 data that has been read out from the memory devices 208. Also, the disk control section 203 transmits to the channel control section 201 notifications, such as, for example, a data write completion notification and a data read completion notification. The disk control section 203 may be equipped with a function to control the memory devices 208 with RAID levels (for example, 0, 1, 5) stipulated in the so-called RAID (Redundant Array of Inexpensive Disks) method.
The memory devices 208 may be, for example, hard disk devices. The memory devices 208 may be provided in one piece with or separately as independent devices from the disk array device. Storage regions provided by the memory devices 208 at each site are managed in units of logical volumes 209, which are volumes that are logically set on the storage regions. Data can be written in or read from the memory devices 208 by designating LUNs (Logical Unit Numbers) that are identifiers appended to the corresponding logical volumes 209. Also, the logical volumes 209 are managed in units of a predetermined data amount such as units of 512 Kb, such that input and output of data in this predetermined unit are conducted. Each of the units is called a logical block, and each of the logical blocks is appended with a logical block address (hereafter referred to as a “LBA”) that indicates positional information of the logical block.
The management terminal 207 may be a computer for maintaining and managing the disk array device and the memory devices 208. Changes in the software and parameters to be executed by the channel control section 201 and the disk control section 203 can be conducted by giving instructions from the management terminal 207. The management terminal 207 can be in a form that is built in the disk array device, or can be provided independently from the disk array device.
The remote communications interface 202 is a communications interface (i.e., a channel extender) that is used for data transfer to another storage device. A copy of data is transferred in a remote copy operation to be described below through this remote communications interface 202. The remote communications interface 202 converts the interface of the channel control section 201 (for example, an interface such as an ESCON® interface or a FICON® interface) to a communications method of the second network 60, whereby data transfer with the other storage device can be realized.
Besides the structure described above, the disk array device may have a structure that functions as a NAS (Network Attached Storage) configured to accept data input/output requests through designating file names from the information processing device 11 according to a relevant protocol such as a NFS (Network File System).
The shared memory 204 can be accessed from both of the channel control section 201 and the disk control section 203. The shared memory 204 is used for delivering data input/output request commands, as well as for storing management information for the storage devices 10 and 20, and the memory devices 208. In the present embodiment, the shared memory 204 stores a LUN map information table 301 shown in FIG. 3, a command device management table 501 shown in FIG. 5, and a pair management table 1001 shown in FIG. 10.
[Virtual Volume]
As described above, the logical volumes 209 are storage regions that are logically set on the physical volumes. Also, by using “virtual volumes” as logical volumes, the storage devices 10 and 20 on which the logical volumes 209 are set can be differentiated from other storage devices that are equipped with physical volumes correlated with the logical volumes 209.
To realize this function, the first storage device 10 stores a LUN map information table 301 shown in FIG. 3. The LUN map information table 301 describes information relating to the logical volumes 209 that are handled by the first storage device 10. For example, in the present embodiment, the LUN map information table 301 includes entries of “LUN,” “Target” and “Mapping LUN.”
Each entry at “LUN” describes a LUN for each of the logical volumes. When a logical volume 209 is a virtual volume, a storage device that is equipped with the logical volume 209 correlated with the virtual volume is set at “Target.” Furthermore, a LUN of the logical volume 209 correlated with the virtual volume is set at “Mapping LUN.” In other words, when there is a description at “Mapping LUN,” it means that the corresponding logical volume is a virtual volume.
Details of the LUN map information table 301 may be registered, for example, by an operator through the management terminal 207 that is connected to the first storage device 10.
The first storage device 10 uses the LUN map information table 301 described above and provides the second logical volume 40 of the second storage device 20 to the information processing device 11 by a mechanism to be described below as if the second logical volume 40 were the first logical volume 30 of the storage device 10. In other words, the information processing device 11 can make data input/output requests, which are to be issued to the logical volume 209 of the second storage device 20, to the first storage device 10.
Processings by the storage device system, which take place when a data input/output request transmitted from the information processing device 11 is a data write request, will be described with reference to FIG. 4.
The information processing device 11 is equipped with a first write request section 401 that writes data in the first storage device 10 according to a first communications protocol. Upon receiving a data write request from the first write request section 401 (S401), the first storage device 10 writes in the cache memory 205 data to be written that has been received with the data write request.
A data transfer section 402 of the first storage device 10 refers to the LUN map information table 301, and confirms as to whether or not a mapping LUN is set for a first logical volume 30 that is set in the data write request. If a second logical volume 40 is set as the mapping LUN, the data transfer section 402 transfers to a second write request section 403 a request to write the data in the second logical volume 40 according to a second communications protocol. In this embodiment, the second write request section 403 makes data write requests to the second storage device 20 according to the second communications protocol. The second storage device 20 receives the data write request from the second write request section 403, and writes the data in the second logical volume 40 (S402).
It is noted that the first communications protocol and the second communications protocol are for example WRITE commands stipulated by a SCSI standard. Accordingly, the data write interfaces at the first storage device 10 and the second storage device 20 do not need to be changed.
The write processing has been so far described. It is noted however that a read processing to read data from a logical volume is also performed in a manner similar to the write processing except that data is transferred in an opposite direction with respect to the data transfer direction in the write processing.
As describe above, in the storage device system in accordance with the present embodiment, the information processing device 11 accesses the second logical volume as if the second logical volume were a logical volume on the first storage device 10.
[Command Device]
Each of the storage devices 10 and 20 is equipped with a “command device” for controlling special commands. The command device is used to convey commands from the information processing device 11 to the storage devices 10 and 20, and the storage devices 10 and 20 can execute commands that are stored in the command devices. What makes the special commands different from ordinary commands is that the command devices are the logical volumes 209. Functions of the command device will be described below.
FIG. 5 shows a command device management table 501 that is stored in each of the storage devices 10 and 20. The command device management table 501 contains entries such as “Device” and “Command Device LUN.” Entries at “Device” indicate as to which of the storage devices 10 and 20 correspond to which of the command devices. Each entry at “Command Device LUN” sets a LUN of each logical volume 209 which expresses the entity of the corresponding command device.
Details of the command device management table 501 may be registered, for example, by an operator through the management terminal 207 that is connected to each of the storage devices 10 and 20.
The command device management table 501 of each of the storage devices 10 and 20 can register command devices of other storage devices (that may be similar to the storage device 10 or 20). When the command devices of the other storage devices are registered, LUNs of virtual volumes, which correspond to the LUNs of the command devices of the other storage devices are registered at the entries “Command Device LUN.”
FIG. 6 shows an example of a command device interface 601, which is a data format of data that is written in a command device. The command device interface 601 is composed of a control parameter, an input parameter, and edited data. The control parameter is composed of a “process number” that indicates a command to be executed by a relevant storage device, and a “presence or absence of edited data” that indicates whether or not data is outputted as a result of the execution of the command. The input parameter sets parameter information that is used when executing the command. Also, the edited data sets data that is outputted as a result of executing the command.
An outline of a process flow to execute a command using a command device will be described with reference to FIG. 7. The information processing device 11 is equipped with a command setting section 701 and a command transmission section 702. The command setting section 701 generates data that sets in a command interface 601 a “process number” of a command to be executed by the first storage device 10 and its “presence or absence of edited data.” The command transmission section 702 transmits to the first write request section 401 a request to write the data in a first logical volume, which is a command device of the first storage device 10, according to a first communications protocol.
The first storage device 10 is equipped with a command execution section 703. The command execution section 703 is equipped with a pair management section 704, a copy forming section 705, a restore section 706, a journal storing section 707, a journal acquisition section 708 and a journal stop section 709, which control pairs of the logical volumes 209 to be described below.
The command execution section 703 refers to a command device management table 501, and obtains a LUN of a command device that corresponds to the first storage device 10 (S701). The command execution section 703 refers to the command device (S702) and, if data in the form of the command device interface 601 exists, executes a command designated by a process number indicated in the data.
Referring to flow charts in FIGS. 8 and 9, processes executed by the information processing device 11 and the storage devices 10 and 20 will be described. First, the information processing device 11 sets a “process number” and a “presence or absence of edited data” in first data in the form of the command device interface 601 (S801). Then, the information processing device 11 refers to a command device management table 501 stored in the storage device 10, and obtains a LUN of a relevant command device of a storage device which executes the command. In order to write the created first data at the LUN obtained, the information processing device 11 transmits to the storage device 10 a write request designating the LUN (S802).
Upon receiving the write request, the storage device 10 writes the first data in the command device at the designated LUN.
It is noted that command devices are logical devices that are defined on storage areas of a plurality of storage devices, like the logical volumes 209, and write requests to the command devices are transmitted based on the same communications protocol as that for write requests transmitted to the logical volumes 209.
The storage device 10 refers to the command device management table 501, to specify LUNs of command devices that the storage device 10 itself should refers to, and monitors whether or not the command devices have data written therein (S901). When the first data is found written in any of the command devices under observation, the storage device 10 executes the command designated by the process number in the first data (S902). Having completed the execution of the command, the storage device 10 confirms whether edited data of the first data is present or absent (S903). When edited data is absent, the storage device 10 deletes the first data from the command device (S906). When edited data is present, the storage device 10 sets data outputted as a result of execution of the command as edited data (S904).
The information processing device 11 confirms whether edited data for the command is present or absent (S803); and transmits to the storage device 10 a read request to read the edited data of the first data when the edited data is present (S804). Upon receiving the edited data from the storage device 10 (Yes at S805), the information processing device 11 completes the processing. It is noted that the read request is transmitted based on the same communications protocol for read requests for the logical volumes 209 other than the command device.
When the edited data exists, after receiving the read request for the edited data from the information processing device 11 (S905), the storage device 10 deletes the first data from the command device (S906).
In this manner, read or write requests that are used by the information processing device 11 for reading or writing data from and to ordinary logical volumes of the storage device 10, the information processing device 11 can transfer commands to the storage device 10.
Also, by using the virtual volumes, the information processing device 11 can transfer commands to the second storage device 20 through the first storage device 10, such that the second storage device 20 can execute the commands.
It is noted that, when the information processing device 11 requests the storage device 10 and 20 to execute a “pair formation,” “journal acquisition,” “acquisition of processing state of journal,” “restore” or “swap” processing to be described below, the information processing device 11 uses the virtual volumes and command devices.
[Pair Formation]
Next, a description will be made as to a method for storing a copy of data in the logical volume 209 of the first storage device 10 in the logical volume 209 of the second storage device 20.
FIG. 10 shows a pair management table 1001. In the pair management table 1001, a column of “COPY SOURCE DEVICE” indicates storage devices (10 or 20) to which those of the logical volumes of copy sources belong (hereafter referred to as “primary volumes”). A column of “COPY DESTINATION DEVICE” indicates storage devices (10 or 20) to which those of the logical volumes of copy destinations belong (hereafter referred to as “auxiliary volumes”). Also, a column of: “PRIMARY LUN” indicates LUNs of the corresponding primary volumes, and a column of “AUXILIARY LUN” indicates LUNs of the corresponding auxiliary volumes. Each correspondence between a primary volume and an auxiliary volume is called a “pair”. Those of the logical volumes 209 for storing journals (to be described below) are assigned to the primary volumes and auxiliary volumes. A column of “PRIMARY JOURNAL LUN” sets LUNs of the logical volumes 209 of the journals assigned for the primary volumes (hereafter referred to as “primary journals”). A column of “AUXILIARY JOURNAL LUN” sets LUNs of the logical volumes 209 of the journals assigned to the auxiliary volumes (hereafter referred to as “auxiliary journals”).
Any one of appropriate methods for assigning the logical volumes 209 for storing the journals can be used. For example, the user himself/herself may designate those of the logical volumes 209 to be used as the journals, or the information processing device 11 may select appropriate unused ones of the logical volumes 209.
Referring to FIG. 11, an example of a process flow in forming pairs will be described. In this example, it is assumed that the first storage device 10 is equipped with a third logical volume and a fifth logical volume, and the second storage device 20 is equipped with a fourth logical volume and a sixth logical volume. The information processing device 11 transmits a command to the first storage device 10 and the second storage device 20 for forming a pair of the third logical volume as being a primary volume 1101 and the fourth logical volume as being an auxiliary volume 1102, and a pair of the fifth logical volume as being a primary journal 1103 and the sixth logical volume as being an auxiliary journal 1104 (1101, 1102). The pair management sections 704 of the first and second storage devices 10 and 20 store information indicating the states of the pairs in the pair management tables 1001 of the respective storage devices 10 and 20. The copy forming section 705 of the second storage device 20 transmits to the first storage device 10 a read request to read data in the primary volume; and upon receiving from the first storage device 10 a copy of the data in the primary volume, the second storage device 20 writes the data in the auxiliary volume (S1103). By this operation, the data in the primary volume and the data in the auxiliary volume can be matched with each other. A processing that brings the primary volume in conformity with the auxiliary volume by a pair forming instruction is called an “initial copy” processing.
Also, the journal storage section 707 of the first storage device 10 starts a processing to obtain a copy of the data written in the primary volume and its positional information in the primary journal. The correlation between the primary volume and the primary journal is described hereunder with reference to FIG. 12. The primary journal is composed of a meta data region 1201 and a journal data region 1202. The journal storage section 707 of the first storage device 10 stores a copy of the data written in the primary volume (hereinafter referred to as “journal data”) in the journal data region 1202. Also, the journal storage section 707 of the first storage device 10 stores in the meta data region 1201 the time when data 1203 is updated in the primary volume, LBA(s) 1204 of the data 1203, LBA(s) 1205 of the journal data 1206 in the corresponding journal data region, and the data length of the updated data. Also, the auxiliary journal is composed of a meta data region 1201 and a journal data region 1202 like the primary journal.
Also, by using a method similar to the above, a copy of data in the logical volume 209 of the second storage device 20 can be stored in the logical volume 209 of the first storage device 10 by an instruction from the information processing device 11.
As a result, without performing data communications between plural information processing devices, and without adding new commands to the operating system of the information processing device 11, data stored in a storage device at a primary site can be stored as a backup in a storage device at a remote site. Also, in accordance with the present embodiment, a storage device at a remote site transmits a read request to a storage device at a primary site to thereby perform a copy forming processing. By this, the processing load on the storage device at the primary site during the copy forming processing is alleviated. In other words, in a method in which a storage device at a primary site writes data in a storage device at a remote site, the storage device at the primary site needs to write the data in the storage device at the remote site after it confirms that the storage device at the remote site is ready for forming a pair. For this reason, the processing load on the storage device at the primary site becomes heavier, which would affect the overall performance of the primary site that is performing other primary processings. In contrast, in accordance with the present embodiment, since the storage device at the primary site only has to send data in response to a read request from the storage device at the remote site, the processing load at the storage device at the primary site can be alleviated.
[Restoration]
Even after the copy forming processing is performed, the first storage device 10 accepts write requests from the information processing device 11, and updates the data in the primary volumes. For this reason, the data in the primary volumes becomes inconsistent with the data in the auxiliary volumes. As described above, the primary journal stores journal data for executions performed even after the copy forming processing took place. In this respect, the second storage device 20 copies data stored in the primary journal into the auxiliary journal, and writes the data stored in the auxiliary journal into the auxiliary volumes, such that updates of the data on the primary volumes can be likewise performed on the auxiliary volumes.
Here, a processing to copy data stored in the primary journal into the auxiliary journal by the second storage device 20 is referred to as a “journal acquisition” processing, and a processing to write journal data stored in the auxiliary journal into the auxiliary volume is referred to as a “restoration” processing.
FIG. 13 shows a flowchart of the journal acquisition processing. The information processing device 11 transmits a journal acquisition instruction to the second storage device 20 (S1301). Upon receiving the journal acquisition instruction, the journal acquisition section 708 of the second storage device 20 refers to the pair management table 1001, and obtains a primary journal LUN of the corresponding pair. The journal acquisition section 708 of the second storage device 20 transmits to the first storage device 10 a read request to read the primary journal. Upon receiving a copy of data of the primary journal, the journal acquisition section 708 of the second storage device 20 writes the data in the auxiliary journal (S1302).
Next, referring to FIG. 14, a processing flow of a restoration processing will be described. The information processing device 11 transmits to the second storage device 20 a restore instruction to restore data in the auxiliary journal onto the auxiliary volumes (S1401). Upon receiving the restore instruction, the restore section 706 of the second storage device 20 writes journal data stored in the auxiliary journal into the auxiliary volumes.
FIG. 15 shows journal data regions 1202 for the primary journal and the auxiliary journal. The journal data regions for the primary journal and the auxiliary journal are defined by the same head LBA and end LBA, respectively. The journal data region 1202 for the primary journal is composed of journal storage completed regions 1502, 1503 and 1504 which store journal data, and purge completed regions 1501 which do not store journal data.
The journal data region 1202 of the auxiliary journal is composed of restoration completed regions 1521 that store journal data that have already been used for restoration in the auxiliary volumes, restore in-progress region 1522 that stores journal data that are designated for restoration, read completed region 1523 that stores journal data that are not designated for restoration, and read in-progress region 1524 that stores journal data that are being read from the primary journal in response to a journal acquisition instruction.
Each of the storage devices 10 and 20 stores journal data in the journal data region 1202 from the head LBA to the end LBA in a chronological order as the journal data is created. When the journal data reaches the end LBA, each of the storage devices 10 and 20 returns to the head LBA again, and stores journal data from there. In other words, the storage devices 10 and 20 use the journal data regions cyclically between the head LBA and the end LBA.
The first storage device 10 that is equipped with the primary journal stores a journal-out LBA 1511 which is a head LBA of the journal storage completed regions 1502, 1503 and 1504, and a journal-in LBA 1512 which is a head LBA of the purge completed region 1501. When the journal-out LBA and the journal-in LBA are equal to each other, it means that journal data is not stored in the primary journal.
The second storage device 20 that is equipped with the auxiliary journal stores a restoration completed LBA 1531 which is the highest LBA of the restoration completed region 1521, a to-be restored LBA 1532 which is the highest LBA of the restore in-progress region 1522, a read completed LBA 1533 which is the highest LBA of the read completed region 1523, and a to-be read LBA 1534 which is the highest LBA of the read in-progress region 1524.
In other words, when the restoration completed LBA 1531 and the to-be restored LBA 1532 are equal to each other, it means that a restoration processing instructed by the information processing device 11 has been completed. Also, when the read completed LBA 1533 and the to-be read LBA 1534 are equal to each other, it means that a journal acquisition processing instructed by the information processing device 10 has been completed.
The information processing device 11 can transmit to the first storage device 10 and the second storage device 20 a request to obtain the processing state of journal. Each of the storage devices 10 and 20 confirms the states of LBAs that indicate the boundaries of the regions described above, and responds to the request.
Also, since the storage devices 10 and 20 use the journal data regions cyclically as described above, regions that become unnecessary need to be released. The processing to release a region is called a “purge” processing. Each of the storage devices 10 and 20 can perform a purge processing by changing addresses of LBAs that indicate the boundaries of the regions. The first storage device 10 can purge the journal storage completed region 1502, among the journal storage completed regions 1502, 1503 and 1504 of the primary journal, which the second storage device 20 has completed acquiring the journal data into the auxiliary journal. In this case, the first storage device 10 changes the journal-out LBA 1511 to the head LBA of the journal storage completed region 1503, such that the journal storage completed region 1502 becomes the purge completed region 1501. The second storage device 20 treats the restoration completed region 1521 of the auxiliary journal as a region that is purged, and stores the journal data obtained in response to the journal acquisition instruction in the restoration completed region 1521.
Referring to a flowchart in FIG. 16, flows of the journal acquisition processing and the restoration processing will be described. The information processing device 11 transmits to the first storage device 10 a request to obtain the processing status of the primary journal (S1601). The information processing device 11 transmits to the first storage device 10 a read request to read edited data of a command device at which the processing status of the primary journal is set (S1602). Upon receiving the edited data of the command device from the first storage device 10 (S1603), the information processing device 11 transmits to the second storage device 20 a journal acquisition request to obtain journal data starting at the journal-out LBA 1511 to a LBA immediately before the journal-in LBA 1512 (S1604). The information processing device 11 transmits to the second storage device 20 a request to obtain the processing status of the auxiliary journal (S1605). The information processing device 11 transmits to the second storage device 20 a read request to read edited data of a command device at which the processing status of the auxiliary journal is set (S1606). Upon receiving the edited data of the command device from the second storage device 20 (S1607), the information processing device 11 compares the read completed LBA 1533 and the to-be read LBA 1534 set in the edited data, to confirm whether or not acquisition of the journal data has been completed (S1608). When the acquisition of the journal data has been completed, the information processing device 11 transmits to the second storage device 20 a restore request to restore journal data up to the read completed LBA 1533 (S1609). Then, the information processing device 11 transmits to the first storage device 10 a purge request to purge the journal data up to the read completed LBA 1533 (S1610). The information processing device 11 repeats the journal acquisition processing and restoration processing.
By the processings described above, updated data in a storage device at a primary site can be reflected on a storage device at a remote site without performing data communications between multiple information processing devices, and without adding new commands to the operating system of the information processing devices. It is noted that, with an instruction from the information processing device 11 that is communicatively connected to a storage device at a remote site, the storage device at the remote site can obtain journal data from a storage device at a primary site and restore the data.
[Swap]
Let us assume that a primary volume of the first storage device 10 and an auxiliary volume of the second storage device 20 form a pair by an instruction from an information processing device 11 (hereafter referred to as a “first information processing device”) that is communicatively connected to the first storage device 10. In this case, if a failure occurs in the first information processing device 10, an information processing device 11 (hereafter referred to as a “second information processing device”) that is communicatively connected to the second storage device 20 can continue processings that have been performed by the first information processing device, using the auxiliary volume of the pair. In this instance, the second information processing device switches the relation between the primary volume and the auxiliary volume. In other words, a pair is formed with the logical volume 209 of the second storage device 20 being a primary volume and the logical volume 209 of the first storage device 10 being an auxiliary volume. Such a processing to switch the pair relation is called a “swap” processing.
Referring to FIGS. 17 and 18, a flow of processings to swap a pair will be described. As shown in FIG. 17, the second information processing device 11 transmits a pair swap instruction to the first storage device 10 and the second storage device 20 (S1701, S1702). Upon receiving the pair swap instruction, the journal stop section of the first storage device 10 stops storing journals in the primary volume. Also, the pair management section 704 of the first storage device 10 swaps the primary volume and the auxiliary volume registered in the pair management table 1001. Similarly, the pair management section 704 of the second storage device 20 swaps the primary volume and the auxiliary volume registered in the pair management table 1001. The journal storage section 707 of the second storage device 20 starts storing journals of the logical volume 209 of the second storage device 20, which defines the primary volume.
FIG. 18 shows a state in which a pair is formed with the logical volume 209 of the second storage device 20 being the primary volume and the logical volume 209 of the first storage device 10 being the auxiliary volume, as a result of the swap processing performed by the first storage device 10 and the second storage device 20 which received the pair swap instruction.
The swap processing performed by the second information processing device 20 and the storage devices 10 and 20 will be described in detail with reference to flowcharts in FIGS. 19 through 21. The second information processing device executes the journal acquisition processing and the restoration processing described above (S1901). The second information processing device transmits to the second storage device 20 a request to obtain the processing status of the auxiliary journal (S1902). The second information processing device transmits to the second storage device 20 a read request to read edited data of a command device in which the processing status of the auxiliary journal is set (S1903). Upon receiving the edited data of the command device from the second storage device 20 (S1904), the second information processing device compares the restoration completed LBA 1531 and the to-be restored LBA 1532 set in the edited data, to confirm if the restoration processing has been completed (S1905). If the restoration has been completed, the second information processing device transmits a pair swap request to the first storage device 10 and the second storage device 20 (S1906, S1907). Upon receiving the pair swap request, the first storage device 10 stops its journal acquisition processing with respect to the primary volume (S2001), and swaps the relation between the copy source and the copy destination registered in the pair management table 1001 (S2002). Also, the second storage device 20, that has received the pair swap request, swaps the relation between the copy source and the copy destination registered in the pair management table 1001 (S2101), and starts a journal acquisition processing with respect to the primary volume of the second storage device 20 (S2102).
Let us consider as an example an information processing system that is composed of a primary site and a remote site. The primary site is equipped with a first information processing device and a first storage device 10, and the remote site is equipped with a second information processing device and a second storage device 20. When a failure occurs in the first information processing device, the second information processing device uses the second storage device 20 to continue primary processings performed at the primary site. The second information processing device may instruct the first storage device 10 and the second storage device 20 to execute the swap instruction described above, such that the second storage device 20 is used for the primary processings, and data on the second storage device 20 can be stored as a backup in the first storage device 10. Furthermore, since the data on the second storage device 20 is stored as a backup in the first storage device 10, the execution of the primary processings can be quickly switched to the primary site, when the first information processing device is recovered from the failure.
Also, since the pair swap instructions from the information processing device 11 to the storage devices 10 and 20 are provided using read/write commands with which the information processing device 11 is equipped, there is no need to add new commands to the operating system on the information processing device 11.
While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.
The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

## Claims

1. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume;
said first controller having a first information indicating that said first logical volume functions as a primary logical volume and a second information indicating that said second logical volume functions as a logical volume being used to transfer data;
said first controller receiving data, which are sent from said first information processing device and are targeted to said first logical volume, and storing data corresponding to said data sent from said first information processing device in said first portion of said first disk drives and storing data corresponding to said data sent from said first information processing device in said second portion of said first disk drives and transferring data corresponding to said data stored in said second portion of said first disk drives to a second storage device;
said second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
said second controller having a third information indicating that said third logical volume functions as a logical volume being used to receive data and a fourth information indicating that said fourth logical volume functions as a secondary logical volume forming a pair relationship with said primary logical volume; and
said second controller receiving said data transferred from said first controller and storing data corresponding to said data transferred from said first controller in said third portion of said second storage device and storing data corresponding to said data stored in said third portion of said second disk drives in said fourth portion of said second storage device;
wherein said first storage device and said second storage device change said first information, said second information, said third information and said fourth information based on at least one command sent from said second information processing device so that said second information processing device sends data targeted to said fourth logical volume, if said first information processing device has a failure
wherein said changed first information indicates that said first logical volume now functions as said secondary logical volume,
wherein said changed second information indicates that said second logical volume now functions as said logical volume being used to receive data,
wherein said changed third information indicates that said third logical volume now functions as said logical volume being used to transfer data, and
wherein said changed fourth information indicates that said fourth logical volume now functions as said primary logical volume.

2. A storage system according to claim 1, wherein: said first and/or second controller have a pair management information of relationship with said first logical volume and said fourth logical volume.

3. A storage system according to claim 1, wherein:
said first and/or second controller have a pair management information, which indicates whether it is under copying data from said first logical volume to said fourth logical volume or not.

4. A storage system according to claim 1, wherein:
said first and/or second controller have a pair management information of whether it is under restoring data from said first logical volume to said fourth logical volume or not.

5. A storage system according to claim 1, wherein:
said first controller has a pair management information of relationship between said first logical volume and said second logical volume.

6. A storage system according to claim 1, wherein:
said first and/or second controller have a pair management information, which indicates whether it is under copying data from said fourth logical volume to said first logical volume or not.

7. A storage system according to claim 1, wherein:
said first controller has a pair management information of whether it is under copying data corresponding to said first logical volume to said second logical volume or not.

8. A storage system according to claim 1, wherein:
said second information processing device sends said command, which are used to change a pair management information including said first information, said second information, said third information and said fourth information.

9. A storage system according to claim 1, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, before changing said first information, said second information, said third information and said fourth information.

10. A storage system according to claim 1, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives stored data, which will be stored from said third logical volume to said fourth logical volume, by at least one pointer before changing said first information, said second information, said third information and said fourth information.

11. A storage system according to claim 1, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, by at least one pointer before changing said first information, said second information, said third information and said fourth information, and
said regions stored data include a plurality of regions in which said data corresponding to said data sent from said first information processing device are under storing by said first controller.

12. A storage system according to claim 1, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives in which said data sent from said first controller are under storing by said second controller, before changing said first information, said second information, said third information and said fourth information.

13. A storage system according to claim 1, wherein:
said second controller transfers said command sent from said second information processing device to said first storage device based on contents of said first command.

14. A storage system according to claim 1, wherein:
said second controller transfers said command sent from said second information processing device to said first storage device, if an address of said command sent from said second information processing device is a certain address of a fifth logical volume.

15. A storage system according to claim 1, wherein:
said command sent from said second information processing device has an information, which is used to identify said third logical volume from a plurality of logical volumes.

16. A storage system according to claim 1, wherein:
each of said logical volumes has a logical unit number, which is used to identify a logical volume from a plurality of logical volumes; and
said command sent from said second information processing device has an information of a plurality of said logical unit number corresponding to said third and fourth logical volumes.

17. A storage system according to claim 1, wherein:
said second controller executes contents of said command sent from said second information processing device, if said command sent from said second information processing device does not have an information of said first storage device.

18. A storage system according to claim 1, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives in which data stored in said third portion of said second disk drives are under storing from said third portion of said second disk drives in said fourth portion of said second disk drives by said second controller.

19. A storage system according to claim 1, wherein:
said second controller, after changing said third information and said fourth information, receives data sent from said second information processing device to said fourth logical volume and stores data corresponding to said data sent from said second information processing device in said fourth portion of said second disk drives and stores data corresponding to said data sent from said second information processing device in said third portion of said second disk drives and transfers data corresponding to said data stored in said third portion of said second disk drives to said first storage device.

20. A storage system according to claim 1, wherein:
said second controller, after changing said third information and said fourth information, receives data sent from said second information processing device to said fourth logical volume and stores data corresponding to said data sent from said second information processing device in said fourth portion of said second disk drives and stores data corresponding to said data sent from said second information processing device in said third portion of said second disk drives and transfers data corresponding to said data stored in said third portion of said second disk drives to said first storage device, and
said first controller, after changing said first information and said second information, receives said data transferred from said second controller and stores data corresponding to said data transferred from said second controller in said second portion of said first storage device and stores data corresponding to said data stored in said second portion of said first disk drives in said first portion of said first storage device.

21. A storage system according to claim 1, wherein:
said data stored in said second logical volume is appended an update information, which is used to maintain a consistency when said data stored in said third portion of said second disk drives are stored in said fourth portion of said second disk drives.

22. A storage system according to claim 1, wherein:
said second logical volume and said third logical volume each function as a journal volume in which a journal data stored.

23. A storage system, comprising:
a first storage device coupled to a first information processing device and having a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume;
a first controller having a first information indicating that said first logical volume functions as a primary logical volume and a second information indicating that said second logical volume functions as a logical volume being used to transfer data;
a second storage device coupled to a second information processing device and said first storage device and having a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume; and
a second controller having a third information indicating that said third logical volume functions as a logical volume being used to receive data and a fourth information indicating that said fourth logical volume functions as a secondary logical volume corresponding to said primary volume,
wherein said first controller receives data sent from said first information processing device to said first logical volume and storing said data sent from said first information processing device in said first logical volume and storing data corresponding to said data sent from said first information processing device in said second logical volume and transferring said data stored in said second logical volume to a second storage device.
wherein said second controller receiving said data transferred from said first controller and storing said data transferred from said first controller in said third logical volume and storing data corresponding to said data stored in said third logical volume in said fourth logical volume,
wherein said first storage device and said second storage device change said first information, said second information, said third information and said fourth information based on at least one command sent from said second information processing device, if said first information processing device has a failure,
wherein said changed first information indicates that said first logical volume now functions as said secondary logical volume,
wherein said changed second information indicates that said second logical volume now functions as said logical volume being used to receive data,
wherein said changed third information indicates that said third logical volume now functions as said logical volume being used to transfer data,
wherein said changed fourth information indicates that said fourth logical volume now functions as said primary logical volume,
wherein said second controller, after changing said third information and said fourth information, receives data sent from said second information processing device to said fourth logical volume and stores said data sent from said second information processing device in said fourth logical volume and stores data corresponding to said data sent from said second information processing device in said third logical volume and transfers said data stored in said third logical volume to said first storage device, and
wherein said first controller, after changing said first information and said second information, receives said data transferred from said second controller and stores said data transferred from said second controller in said second logical volume and stores data corresponding to said data stored in said second logical volume in said first logical volume.

24. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume;
said first controller having a first information indicating that said second logical volume functions as a logical volume being used to transfer data;
said first controller receiving data sent from said first information processing device to said first logical volume and storing said data sent from said first information processing device in said first logical volume and storing data corresponding to said data sent from said first information processing device in said second logical volume and transferring said data stored in said second logical volume to a second storage device;
said second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
said second controller having a second information indicating that said third logical volume functions as a logical volume being used to receive data; and
said second controller receiving said data transferred from said first controller and storing said data transferred from said first controller in said third logical volume and storing data corresponding to said data stored in said third logical volume in said fourth logical volume;
wherein said first storage device and said second storage device change said first information and said second information based on at least one command sent from said second information processing device so that said second information processing device sends data targeted to said fourth logical volume, if said first information processing device has a failure,
wherein said changed first information indicates that said second logical volume functions as said logical volume being used to receive data, and
wherein said changed second information indicates that said third logical volume functions as said logical volume being used to transfer data.

25. A storage system according to claim 24, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, by using at least one pointer before changing said first information and said second information.

26. A storage system according to claim 24, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives stored data, which will be stored from said third logical volume to said fourth logical volume, before changing said first information and said second information.

27. A storage system according to claim 24, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, before changing said first information and said second information, and
said regions in said second portion of said first disk drives include a plurality of regions in which said data sent from said first information processing device are under storing by said first controller.

28. A storage system according to claim 24, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives in which said data sent from said first controller are under storing by said second controller, by at least one pointer before changing said first information and said second information.

29. A storage system according to claim 24, wherein:
said data stored in said second logical volume is appended an update information, which is used to maintain a consistency when said data stored in said third logical volume are stored in said fourth logical volume.

30. A storage system according to claim 24, wherein:
said second logical volume and said third logical volume each function as a journal volume in which a journal data stored.

31. A storage system according to claim 24, wherein:
said command sent from said second information processing device is targeted to said second storage device.

32. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume; and
a second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
wherein said storage system has a first status including that
said first logical volume functions as a primary logical volume being stored data sent from a primary information processing device, if said first information processing device functions as said primary information processing device sending data,
said second logical volume functions as a transferring logical volume in which data corresponds to an updated data stored in said primary logical volume are stored,
said third logical volume functions as a receiving logical volume in which data corresponds to said data stored in said transferring logical volume are stored, and
said fourth logical volume functions as a secondary logical volume, which forms a pair relationship of a remote copy process with said primary logical volume and stores data corresponding to said data stored in said receiving logical volume,

wherein said storage system has a second status including that
said fourth logical volume functions as said primary logical volume, if said second information processing device functions as said primary information processing device,
said third logical volume functions as said transferring logical volume,
said second logical volume functions as said receiving logical volume, and
said first logical volume functions as said secondary logical volume, and

wherein said storage system is changed from said first status to said second status based on one or more commands sent from said second information processing device.

33. A storage system according to claim 32, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, by using at least one pointer during said first status of said storage system.

34. A storage system according to claim 32, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives stored data, which will be stored from said third logical volume to said fourth logical volume, during said first status of said storage system.

35. A storage system according to claim 32, wherein:
said first controller manages a plurality of regions in said second portion of said first disk drives stored data, which will be transferred from said second logical volume to said third logical volume, during said first status of said storage system, and
said regions in said second portion of said first disk drives include a plurality of regions in which said data sent from said first information processing device are under storing by said first controller.

36. A storage system according to claim 32, wherein:
said second controller manages a plurality of regions in said third portion of said second disk drives in which said data sent from said first controller are under storing by said second controller, by at least one pointer during said first status of said storage system.

37. A storage system according to claim 32, wherein:
said data stored in said second logical volume is appended an update information, which is used to maintain a consistency when said data stored in said third logical volume are stored in said fourth logical volume.

38. A storage system according to claim 32, wherein:
said second logical volume and said third logical volume each function as a journal volume in which a journal data stored.

39. A storage system according to claim 32, wherein:
said commands sent from said second information processing device is targeted to said second storage device.

40. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume; and
a second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
wherein said storage system has a first status including that
said first logical volume functions as a primary logical volume being stored data sent from a primary information processing device, if said first information processing device functions as said primary information processing device sending data,
said second logical volume functions as a transferring logical volume being stored data, which corresponds to an updated data stored in said primary logical volume and is transferred to said second storage device,
said third logical volume functions as a receiving logical volume being stored data, which is received from said first storage device, and
said fourth logical volume functions as a secondary logical volume, which forms a pair relationship with said primary logical volume and is stored data from said receiving logical volume,

wherein said storage system has a second status including that
said fourth logical volume functions as said primary logical volume, if said second information processing device functions as said primary information processing device,
said third logical volume functions as said transferring logical volume,
said second logical volume functions as said receiving logical volume, and
said first logical volume functions as said secondary logical volume, and

wherein said storage system is changed from said first status to said second status if said first information processing device has a failure.

41. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume; and
a second storage device coupled to said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
wherein said storage system performs a first asynchronous remote copy process according to a first status in which
said first logical volume functions as a primary logical volume which stores data sent from said first information processing device,
said second logical volume functions as a transferring logical volume which stores data, corresponding to updated data stored in said primary logical volume and to be transferred to said second storage device,
said third logical volume functions as a data storing logical volume in which stores data corresponding to at least one data of an auxiliary logical volume, and
said fourth logical volume functions as said auxiliary logical volume, which forms a pair relationship with said primary logical volume and stores data corresponding to data previously stored in said primary logical volume,

wherein said storage system performs a second asynchronous remote copy process according to a second status in which
said fourth logical volume functions as said primary logical volume,
said third logical volume functions as said transferring logical volume which stores data which is to be transferred to said first storage device,
said second logical volume functions as said data storing logical volume, and
said first logical volume functions as said auxiliary logical volume, and wherein said storage system is changed from said first status to said second status based on one or more commands.

42. A storage system according to claim 41, wherein:
said first controller manages a plurality of regions in said second logical volume which store data, which will be transferred from said second logical volume to said second storage device, by using at least one pointer during said first status of said storage system.

43. A storage system according to claim 41, wherein:
said second controller manages a plurality of regions in said third logical volume during said first status of said storage system.

44. A storage system according to claim 41, wherein:
said first controller manages a plurality of regions in said second logical volume which store data, which will be transferred from said second logical volume to said second storage device, during said first status of said storage system, and
said regions in said second logical volume include a plurality of regions in which said data sent from said first information processing device are being stored by said first controller.

45. A storage system according to claim 41, wherein:
said second controller manages a plurality of regions in said third logical volume in which said data corresponding to said at least one data of said auxiliary logical volume are stored, during said first status of said storage system.

46. A storage system according to claim 41, wherein:
said data stored in said second logical volume is appended an update information, which is used to maintain a consistency when said data previously stored in said first logical volume are stored in said fourth logical volume.

47. A storage system according to claim 41, wherein:
said second logical volume function as a journal volume in which a journal data is stored.

48. A storage system according to claim 41, wherein:
said one or more commands are targeted to said second storage device.

49. A storage system according to claim 41, wherein:
said transferring logical volume repeatedly stores data corresponding to each updated data stored in said primary logical volume and one or more data stored in said transferring logical volume are repeatedly transferred to said second storage device during said first asynchronous remote copy process.

50. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical volume and a second portion of said first disk drives being related to a second logical volume; and
a second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical volume and a fourth portion of said second disk drives being related to a fourth logical volume;
wherein said storage system performs a first asynchronous remote copy process according to a first status in which said first logical volume functions as a primary logical volume which stores data sent from said first information processing device,
said second logical volume functions as a transferring logical volume which stores data,, corresponding to updated data stored in said primary logical volume and to be transferred to said second storage device,
said third logical volume functions as a data storing logical volume which stores data corresponding to at least one data of an auxiliary logical volume, and
said fourth logical volume functions as said auxiliary logical volume, which forms a pair relationship with said primary logical volume and stores data corresponding to data previously stored in said primary logical volume,

wherein said storage system performs a second asynchronous remote copy process according to a second status in which
said fourth logical volume functions as a substitute for said primary logical volume which stores data sent from said second information processing device,
said third logical volume functions as a substitute for said transferring logical volume which stores data which is to be transferred to said first storage device,
said second logical volume functions as said data storing logical volume, and
said first logical volume functions as said auxiliary logical volume, and wherein said storage system is changed from said first status to said second status if said first information processing device has a failure and/or if at least one of said first storage device or said second storage device receives at least one command.

51. A storage system according to claim 50, wherein:
said first controller manages a plurality of regions in said second logical volume which store data, which will be transferred from said second logical volume to said second storage device, by using at least one pointer during said first status of said storage system.

52. A storage system according to claim 50, wherein:
said second controller manages a plurality of regions in said third logical volume during said first status of said storage system.

53. A storage system according to claim 50, wherein:
said first controller manages a plurality of regions in said second logical volume which store data, which will be transferred from said second logical volume to said second storage device, during said first status of said storage system, and
said regions in said second logical volume include a plurality of regions in which said data sent from said first information processing device are being stored by said first controller.

54. A storage system according to claim 50, wherein:
said second controller manages a plurality of regions in said third logical volume in which said data corresponding to said at least one data of said auxiliary logical volume are stored, during said first status of said storage system.

55. A storage system according to claim 50, wherein:
said transferring logical volume repeatedly stores data corresponding to each updated data stored in said primary logical volume and one or more data stored in said transferring logical volume are repeatedly transferred to said second storage device during said first asynchronous remote copy process.

56. A storage system according to claim 50, wherein:
said storage system is changed from said first status to said second status if at least one of said first storage device or said second storage device receives said at least one command, said at least one command being sent from said second information processing device.

57. A storage system according to claim 56, wherein:
said second storage device, based on said at least one command, changes said fourth logical volume functioning as said auxiliary logical volume to said fourth logical volume functioning as said primary logical volume and changes said third logical volume functioning as said data storing logical volume to said third logical volume functioning as said transferring logical volume, and
said first storage device, based on a communication with said second storage device, changes said first logical volume functioning as said primary logical volume to said first logical volume functioning as said auxiliary logical volume and changes said second logical volume functioning as said transferring logical volume to said second logical volume functioning as said data storing logical volume, said communication being processed based on said at least one command.

58. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical area and a second portion of said first disk drives being related to a second logical area; and
a second storage device coupled to said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical area and a fourth portion of said second disk drives being related to a fourth logical area;
wherein said storage system performs a first asynchronous remote copy process according to a first status in which
said first logical area functions as a primary logical volume which stores data sent from said first information processing device,
at least one portion of said second logical area functions as a transferring logical area which stores data, corresponding to updated data stored in said primary logical volume and to be transferred to said second storage device,
at least one portion of said third logical area functions as a data storing logical area which stores data corresponding to at least one data of an auxiliary logical volume, and
said fourth logical area functions as said auxiliary logical volume, which forms a pair relationship with said primary logical volume and which stores data corresponding to data already stored in said primary logical volume,

wherein said storage system performs a second asynchronous remote copy process according to a second status in which
said fourth logical area functions as said primary logical volume,
at least one portion of said third logical area functions as said transferring logical area which stores data which is to be transferred to said first storage device,
at least one portion of said second logical area functions as said data storing logical area, and
said first logical area functions as said auxiliary logical volume, and

wherein said storage system is changed from said first status to said second status if at least one of said first storage device or said second storage device receives at least one command.

59. A storage system according to claim 58, wherein:
said first controller manages a plurality of regions in said second logical area which store data, which will be transferred from said at least one portion of said second logical area to said second storage device, by using at least one pointer during said first status of said storage system.

60. A storage system according to claim 58, wherein:
said second controller manages a plurality of regions in said third logical area during said first status of said storage system.

61. A storage system according to claim 58, wherein:
said first controller manages a plurality of regions in said second logical area which store data, which will be transferred from said at least one portion of said second logical area to said second storage device, during said first status of said storage system, and
said regions in said second logical area include a plurality of regions in which said data sent from said first information processing device are being stored by said first controller.

62. A storage system according to claim 58, wherein:
said second controller manages a plurality of regions in said third logical area in which said data corresponding to said at least one data of said auxiliary logical volume are stored, during said first status of said storage system.

63. A storage system according to claim 58, wherein:
said transferring logical area repeatedly stores data corresponding to each updated data stored in said primary logical volume and one or more data stored in said transferring logical area are repeatedly transferred to said second storage device during said first asynchronous remote copy process.

64. A storage system, comprising:
a first storage device coupled to a first information processing device and having a first controller and a plurality of first disk drives, a first portion of said first disk drives being related to a first logical area and a second portion of said first disk drives being related to a second logical area; and
a second storage device coupled to a second information processing device and said first storage device and having a second controller and a plurality of second disk drives, a third portion of said second disk drives being related to a third logical area and a fourth portion of said second disk drives being related to a fourth logical area;
wherein said storage system performs a first asynchronous remote copy process according to a first status in which
said first logical area functions as a primary logical volume which stores data sent from said first information processing device,
at least one portion of said second logical area functions as a transferring logical area which stores data, corresponding to an updated data stored in said primary logical volume and to be transferred to said second storage device,
at least one portion of said third logical area functions as a data storing logical area which stores data corresponding to at least one data of an auxiliary logical volume, and
said fourth logical area functions as said auxiliary logical volume, which forms a pair relationship with said primary logical volume and which stores data corresponding to data previously stored in said primary logical volume,

wherein said storage system performs a second asynchronous remote copy process according to a second status in which
said fourth logical area functions as a substitute for said primary logical volume which stores data sent from said second information processing device,
at least one portion of said third logical area functions as a substitute for said transferring logical area which stores data which is to be transferred to said first storage device,
at least one portion of said second logical area functions as said data storing logical area, and
said first logical area functions as said auxiliary logical volume, and

wherein said storage system is changed from said first status to said second status if said first information processing device has a failure and/or if at least one of said first storage device or said second storage device receives at least one command.

65. A storage system according to claim 64, wherein:
said first controller manages a plurality of regions in said second logical area which store data, which will be transferred from said at least one portion of said second logical area to said second storage device, by using at least one pointer during said first status of said storage system.

66. A storage system according to claim 64, wherein:
said second controller manages a plurality of regions in said third logical area during said first status of said storage system.

67. A storage system according to claim 64, wherein:
said first controller manages a plurality of regions in said second logical area which store data, which will be transferred from said at least one portion of said second logical area to said second storage device, during said first status of said storage system, and
said regions in said second logical area include a plurality of regions in which said data sent from said first information processing device are being stored by said first controller.

68. A storage system according to claim 64, wherein:
said second controller manages a plurality of regions in said third logical area in which said data corresponding to said at least one data of said auxiliary logical volume are stored, during said first status of said storage system.

69. A storage system according to claim 64, wherein:
said transferring logical area repeatedly stores data corresponding to each updated data stored in said primary logical volume and one or more data stored in said transferring logical area are repeatedly transferred to said second storage device during said first asynchronous remote copy process.

70. A storage system according to claim 64, wherein:
said storage system is changed from said first status to said second status if at least one of said first storage device or said second storage device receives said at least one command, said at least one command being sent from said second information processing device.

71. A storage system according to claim 70, wherein:
said second storage device, based on said at least one command, implements said fourth logical area functioning as said primary logical volume instead of said fourth logical area functioning as said auxiliary logical volume and implements said at least one portion of third logical area functioning as said transferring logical area instead of said at least one portion of third logical area functioning as said data storing logical area, and
said first storage device, based on a communication with said second storage device, implements said first logical area functioning as said auxiliary logical volume instead of said first logical area functioning as said primary logical volume and implements said at least one portion of second logical area functioning as said data storing logical area instead of said at least one portion of second logical area functioning as said transferring logical area, said communication being processed based on said at least one command.