Abstract:
Systems and methods for data migration are disclosed. A method may include allocating a destination storage resource to receive migration data. The method may also include assigning the destination storage resource a first identifier value equal to an identifier value associated with a source storage resource. The method may additionally include assigning the source storage resource a second identifier value different than the first identifier value. The method may further include migrating data from the source storage resource to the destination storage resource.

Description:
TECHNICAL FIELD 
     The present disclosure relates in general to storage and processing of data, and more particularly to migrating stored data from one storage resource to another. 
     BACKGROUND 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Information handling systems often use one or more arrays of physical storage resources, for storing information. Arrays of physical storage resources typically utilize multiple disks to perform input and output operations and can be structured to provide redundancy which may increase fault tolerance (e.g., a Redundant Array of Independent Disks or “RAID”). Other advantages of arrays of storage resources may be increased data integrity, throughput, and/or capacity. In operation, one or more physical storage resources disposed in an array of storage resources may appear to an operating system as a single logical storage unit or “virtual storage resource.” Implementations of storage resource arrays can range from a few storage resources disposed in a server chassis, to hundreds of storage resources disposed in one or more separate storage enclosures. In certain cases, one or more arrays of storage resources may be implemented as a storage area network (SAN). A SAN is in effect an array or collection of physical storage resources communicatively coupled to and accessible via a network (e.g., a host information handling system may access the SAN via a network connection). 
     From time to time, an administrator or user of an array of storage resources may desire to migrate data from one storage resource to another. For example, as a storage resource ages and becomes obsolete, it may be desired to copy all of the data from the storage resource to a newer storage resource. However, traditional approaches to data migration have numerous disadvantages. For example,  FIG. 1  depicts a system  100  employing a traditional approach to data migration. In the approach depicted in  FIG. 1 , a migration module  104  on host  102  may manage migration of data from storage resource  110   a  of storage array  108   a  to storage array  108   b . Under this approach, capacity is allocated to the destination storage array  108   b  (e.g., storage resource  110   b  is allocated to storage array  108   b ), and destination storage resource  110   b  is assigned an identifier (e.g., iSCSI qualified name or Fibre Channel World Wide Name) different than that of the source storage resource  110   a . Migration module  104  then reads the data from source storage resource  110   a  and writes it to destination storage resource  110   b  such that migrated data follows path  116 . During migration, a portion of the data being migrated may be the target of an input-output (I/O) operation (e.g., a read request or write request from host  102 ). Accordingly, under the approach of  FIG. 1 , data associated with write requests may be written to both source storage resource  110   a  and destination storage resource  110   b , and the migration module  104  may track which blocks have been written, so as to avoid writing old data over new data during the migration. Data associated with read requests during migration may be read from source storage resource  110   a . After all migrated data is copied to destination storage resource  110   b , migration module  104  may reconfigure host  102  to map to the destination storage resource  110   b , and source storage resource  110   a  may be deleted. 
     The approach of  FIG. 1  has numerous disadvantages. For example, the approach of  FIG. 1  is inefficient because migrated data moves over network  106  twice (first from source storage resource  110   a  to host  102 , then from host  102  to destination storage resource  110   b ). In addition, the approach of  FIG. 1  requires that data associated with write requests be written to both source storage resource  110   a  and destination storage resource  110   b  during migration. Furthermore, this approach comes with a high level of management complexity, as destination storage resource  110   b  is assigned a new identifier, requiring reconfiguration at the host level, network level, and the storage array level. 
     As another example,  FIG. 2  depicts a system  200  employing a traditional approach to data migration. In the approach depicted in  FIG. 2 , a replication module  214  on storage array  208   a  may manage migration of data from storage resource  210   a  of storage array  208   a  to storage array  208   b.  Under this approach, capacity is allocated to the destination storage array  208   b  (e.g., storage resource  210   b  is allocated to storage array  208   b ), and destination storage resource  210   b  is assigned an identifier (e.g., iSCSI qualified name or Fibre Channel World Wide Name) different than that of the source storage resource  210   a . Replication module  214  then reads the data from source storage resource  210   a  and writes it to destination storage resource  210   b  via network  206  such that migrated data follows path  216 . Replication module  214  may use periodic snapshot technology to take periodic point in time snapshots to allow it to maintain a consistent copy of data for migration and allow it to track writes to source storage resource  210   a  during migration of data to destination storage resource  210   b.  Accordingly, under the approach of  FIG. 2 , data associated with write requests may be tracked using the snapshot technology. Initially, data written by host  102  during migration may be written to source storage resource  210   a  if blocks associated with such data have not been migrated, and may replication module  314  may also track writes using snapshot technology. At a certain point (e.g., if the number of blocks written by host  102  becomes small), replication module  214  may block I/O commands from host  102 , complete data migrations, and then reconfigure host  102  to access the new storage resource  110   b.    
     The approach of  FIG. 2  also has numerous disadvantages. For example, the approach of  FIG. 2  is inefficient because all write requests must be tracked with snapshots, which may be quite voluminous during times of heavy write activity. In addition, this approach comes with a high level of management complexity, as destination storage resource  210   b  is assigned a new identifier, requiring reconfiguration at the host level and the storage array level. 
     SUMMARY 
     In accordance with the teachings of the present disclosure, the disadvantages and problems associated with data migration have been substantially reduced or eliminated. 
     In accordance with an embodiment of the present disclosure, a method for migration of data is provided. The method may include allocating a destination storage resource to receive migration data. The method may also include assigning the destination storage resource a first identifier value equal to an identifier value associated with a source storage resource. The method may additionally include assigning the source storage resource a second identifier value different than the first identifier value. The method may further include migrating data from the source storage resource to the destination storage resource. 
     In accordance with another embodiment of the present disclosure, a system for migration of data, may include a source storage resource, a destination storage resource, and a migration module configured to manage migration of data from the source storage resource to the destination storage resource. The migration module may be operable to, in response to a request to migrate data: (i) assign the destination storage resource a first identifier value equal to an identifier value associated with the source storage resource; (ii) assign the source storage resource a second identifier value different than the first identifier value; and (iii) migrate data from the source storage resource to the destination storage resource. 
     In accordance with a further embodiment of the present disclosure, a system for migration of data may include a source storage array comprising a source storage resource and a destination storage array. The destination storage array may be configured to: (i) allocate a destination storage resource to receive migration data from the source storage resource; (ii) assign the destination storage resource a first identifier value equal to an identifier value associated with the source storage resource; (iii) assign the source storage resource a second identifier value different than the first identifier value; and (iv) migrate data from the source storage resource to the destination storage resource. 
     Other technical advantages will be apparent to those of ordinary skill in the art in view of the following specification, claims, and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1  illustrates a block diagram of an approach to data migration, as is known in the art; 
         FIG. 2  illustrates a block diagram of another approach to data migration, as is known in the art; 
         FIG. 3  illustrates a block diagram of an example system for migrating data, in accordance with certain embodiments of the present disclosure; 
         FIG. 4  illustrates a flow chart of an example method for migrating data, in accordance with certain embodiments of the present disclosure; 
         FIG. 5  illustrates a flow chart of an example method for performing a read request, in accordance with certain embodiments of the present disclosure; and 
         FIG. 6  illustrates a flow chart of an example method for performing a write request, in accordance with certain embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments and their advantages are best understood by reference to  FIGS. 3-6 , wherein like numbers are used to indicate like and corresponding parts. 
     For the purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a PDA, a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components or the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components. 
     For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing. 
     For the purposes of this disclosure, a processor may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. 
     For the purposes of this disclosure, a memory may include any system, device, or apparatus configured to retain program instructions and/or data for a period of time (e.g., computer-readable media). Memory may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power the memory is turned off. 
     For the purposes of this disclosure, a network interface may include any suitable system, apparatus, or device operable to serve as an interface between an information handling system and a network using any suitable transmission protocol and/or standard. 
     An information handling system may include or may be coupled via a network to one or more arrays of physical storage resources. An array of physical storage resources may include a plurality of storage resources, and may be operable to perform one or more input and/or output storage operations, and/or may be structured to provide redundancy. In operation, one or more storage resources disposed in an array of storage resources may appear to an operating system as a single logical storage unit or “virtual storage resource.” 
     In certain embodiments, an array of storage resources may be implemented as a Redundant Array of Independent Disks (also referred to as a Redundant Array of Inexpensive Disks or a RAID). RAID implementations may employ a number of techniques to provide for redundancy, including striping, mirroring, and/or parity checking. As known in the art, RAIDs may be implemented according to numerous RAID standards, including without limitation, RAID 0, RAID 1, RAID 0+1, RAID 3, RAID 4, RAID 5, RAID 6, RAID 01, RAID 03, RAID 10, RAID 30, RAID 50, RAID 51, RAID 53, RAID 60, RAID 100, etc. 
       FIG. 3  illustrates a block diagram of an example system  300  for migrating data, in accordance with certain embodiments of the present disclosure. As depicted, system  300  may include one or more hosts  302 , a network  306 , and one or more storage arrays  308  each comprising one or more storage resources  310 . 
     Host  302  may comprise an information handling system and may generally be operable to communicate via network  306  to read data from and/or write data to one or more storage resources  310  of storage arrays  308 . In certain embodiments, host  302  may be a server. In another embodiment, host  302  may be a personal computer (e.g., a desktop computer or a portable computer). Host  302  may include any suitable components (e.g., one or more processors, one or more memories, and one or more network interfaces to communicatively couple host  302  to network  306 . Although system  300  is depicted as having one host  302  for purposes of exposition, it is understood that system  300  may include any number of hosts  302 . 
     Network  306  may be a network and/or fabric configured to couple host  302  to one or more of storage arrays  308 . In certain embodiments, network  306  may allow host  302  to communicatively couple to storage resources  310  such that the storage resources  310  appear to host  302  as locally attached storage resources. In the same or alternative embodiments, network  306  may include a communication infrastructure, which provides physical connections, and a management layer, which organizes the physical connections, storage resources  310 , and host  302 . In the same or alternative embodiments, network  306  may allow block I/O services and/or file access services to storage resources  310 . Network  306  may be implemented as, or may be a part of, a storage area network (SAN), personal area network (PAN), local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), a wireless local area network (WLAN), a virtual private network (VPN), an intranet, the Internet, or any other appropriate architecture or system that facilitates the communication of signals, data, and/or messages (generally referred to as data). Network  306  may transmit data using any storage and/or communication protocol, including without limitation, Fibre Channel, Frame Relay, Asynchronous Transfer Mode (ATM), Internet protocol (IP), other packet-based protocol, small computer system interface (SCSI), advanced technology attachment (ATA), serial ATA (SATA), advanced technology attachment packet interface (ATAPI), serial storage architecture (SSA), integrated drive electronics (IDE), and/or any combination thereof. Network  306  and its various components may be implemented using hardware, software, or any combination thereof. 
     Each storage array  308  may include any collection or array of storage resources  310 . Storage resources  310  may include hard disk drives, magnetic tape libraries, optical disk drives, magneto-optical disk drives, compact disk drives, compact disk arrays, disk array controllers, and/or any other system, apparatus or device operable to store data. In some embodiments, one or more of storage resources  310  may comprise a physical storage resource. In the same or alternative embodiments, one or more of storage resources  310  may comprise a virtual storage resource, wherein such virtual storage resource includes a collection of one or more physical storage resources that may appear to host  302  as a single storage resource. Although not depicted in  FIG. 3 , storage enclosures may be configured to hold and power one or more storage resources  310 , and may be communicatively coupled to host  302  and/or network  306 , in order to facilitate communication of data between host  302  and storage resources  310 . In certain embodiments, one or more storage arrays  310  may be coterminous with a storage enclosure. 
     As depicted in  FIG. 3 , storage array  308   b  may include a migration module  314 . Migration module  314  may include any system, device, or apparatus configured to manage migration of data between storage resources  310  in accordance with this disclosure and as described in greater detail elsewhere in this disclosure. In certain embodiments, all or a portion of migration module  314  may be implemented in hardware. In the same or alternative embodiments, all or a portion of migration module  314  may be implemented in software and/or firmware embodied in a computer-readable medium. 
     Also as shown in  FIG. 3 , migration module  314  may include a counter  318  and a bitmap  320 . Counter  318  may include any system, device, or apparatus configured to track the amount of data migrated from one storage resource  310  to another storage resource  310  (e.g., from storage resource  310   a  to storage resource  310   b ) in accordance with this disclosure and as described in greater detail elsewhere in this disclosure. In certain embodiments, all or a portion of counter  318  may be implemented in hardware. In the same or alternative embodiments, all or a portion of counter  318  may be implemented in software and/or firmware embodied in a computer-readable medium. 
     Bitmap  320  may include any system, device, or apparatus configured to track the blocks of a storage resource  310  written to pursuant to an input-output operation during migration (e.g., a write request from host  302  to a destination storage resource  310  during migration) in accordance with this disclosure and as described in greater detail elsewhere in this disclosure. In certain embodiments, all or a portion of bitmap  320  may be implemented in hardware. In the same or alternative embodiments, all or a portion of bitmap  320  may be implemented in software and/or firmware embodied in a computer-readable medium. 
     Although the embodiment shown in  FIG. 3  depicts system  300  having two storage arrays  308  for the purposes of exposition, system  300  may have any suitable number of storage arrays  308 . In addition, although the embodiment shown in  FIG. 3  depicts each storage array  308  having one storage resource  310  for the purposes of exposition, each storage array  308  of network  300  may have any suitable number of storage resources  310 . 
     Although  FIG. 3  depicts host  302  communicatively coupled to storage arrays  308  via network  306  for purposes of exposition, one or more hosts  302  may be communicatively coupled to one or more storage resources  310  without network  306  or other network. For example, in certain embodiments, one or more storage resources  310  may be directly coupled and/or locally attached to one or more hosts  302 . 
       FIG. 4  illustrates a flow chart of an example method  400  for migrating data, in accordance with certain embodiments of the present disclosure. According to one embodiment, method  400  preferably begins at step  402 . As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system  300 . As such, the preferred initialization point for method  400  and the order of the steps  402 - 420  comprising method  400  may depend on the implementation chosen. 
     At step  402 , a message may be communicated requesting migration of data from source storage resource  310   a  to storage array  308   b . For example, the message may be communicated as a result of a command issued by an administrator or user of system  300 . In some embodiments, the message may be communicated from host  302  to storage array  308   a  or storage array  308   b . In other embodiments, an administrator may issue the command from an information handling system or terminal other than host  302 . 
     At step  404 , migration module  314  of storage array  308   b  may receive the message from host  302 . 
     At step  406 , in response to receipt of the migration request message, storage array  308   b  may allocate storage resource  310   b  as the migration destination and assign it the same identifier value as source storage resource  310   a  (e.g, iSCSI qualified name or FibreChannel World Wide Name). 
     At step  408 , storage array  308   a  may instruct host  302  to redirect all input/output requests for source storage resource  310   a  to destination storage resource  310   b . For example, in SCSI embodiments, storage array  308   a  may respond to an input/output request from host  302  intended for source storage resource  310   a  by responding to host  302  with a REDIRECT message. 
     At step  410 , storage array  308   a  or another suitable component of system  300  may change the identifier of source storage resource  310   a  to an identifier value unknown by host  302 , but known to migration module  314  (e.g, iSCSI qualified name or FibreChannel World Wide Name). 
     At step  411 , migration module  314  may initiate counter  318  (e.g., reset counter  318  or set it to zero). 
     At step  412 , migration module  314  may determine whether data in a particular block of storage resource  310   a  has already been replaced by a write operation to destination storage resource  310   b  that has occurred during the migration process. For example, migration module  314  may determine the memory address of the data block and compare the memory address with bitmap  320  to determine whether the bitmap  320  entry corresponding with the memory address indicates that a write operation corresponding to the memory address has been performed. If the data in the block has already been replaced by a write operation, method  400  may proceed to step  418 . Otherwise, if the data in the block has not been replaced by a write operation, method  400  may proceed to step  414 . 
     At step  414 , in response to a determination that the data block has not been replaced by a write operation, migration module  314  may read a block of data from storage resource  310   a , by addressing source storage resource  310   a  with its new private identifier. 
     At step  416 , migration module may write the block to destination storage resource  310   b.    
     At step  418 , in response to the data block written to destination storage resource  310   b  or in response to a determination that the data block has already been replaced by a write operation, migration module  314  may increment counter  318  to indicate the block has been written. 
     At step  420 , migration module  314  may determine if all data associated with the migration has been migrated. For example, migration module  314  may compare the value present in counter  318  (e.g., indicating the number of data blocks migrated) to a value indicative of the amount of data to be migrated (e.g., the number of blocks present in source storage resource  310   a ). If not all data associated with the migration has migrated, method  400  may proceed again to step  412 , where another block of data may be read from source storage resource  310   a . If all data associated with the migration has been migrated, method  400  may end. 
     Although  FIG. 4  discloses a particular number of steps to be taken with respect to method  400 , method  400  may be executed with greater or lesser steps than those depicted in  FIG. 4 . In addition, although  FIG. 4  discloses a certain order of steps to be taken with respect to method  400 , the steps comprising method  400  may be completed in any suitable order. In addition, steps  402 - 420  may be repeated, independently and/or collectively, as often as desired or required by a chosen implementation. 
     Method  400  may be implemented using system  300  or any other system operable to implement method  400 . In certain embodiments, method  400  may be implemented partially or fully in software and/or firmware embodied in computer-readable media. 
       FIG. 5  illustrates a flow chart of an example method  500  for performing a read request during migration of data, in accordance with certain embodiments of the present disclosure. According to one embodiment, method  500  preferably begins at step  502 . As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system  300 . As such, the preferred initialization point for method  500  and the order of the steps  502 - 516  comprising method  500  may depend on the implementation chosen. 
     At step  502 , storage array  308   b  may receive a read request (e.g., from host  302 ) for destination storage resource  310   b  while a migration operation (e.g., method  400 ) is taking place. 
     At step  504 , in response to receiving the read request, migration module  314  may determine whether the data associated with the read request has already been migrated to destination storage resource  310   b . For example, migration module  314  may compare the value present in counter  318  (e.g., indicating the number of data blocks migrated) to a value indicative of data associated with the read request (e.g., a block address associated with the read request), to determine whether the subject data has already been migrated. If the data associated with the read request has not been migrated to destination storage resource  310   b , method  500  may proceed to step  506 . Otherwise, if the data associated with the read request has been migrated to destination storage resource  310   b , method  500  may proceed to step  516 . 
     At step  506 , in response to a determination that the data associated with the read request has not been migrated to destination storage resource  310   b , migration module  314  may communicate the read request to source storage resource  310   a  using the private identifier of the source storage resource  310   a.    
     At step  508 , in response to the read request received from migration module  314 , source storage resource  310   a  may communicate to migration module  314  the data responsive to the read request. 
     At step  510 , migration module  314  may communicate (e.g., to host  302 ) data responsive to the read request. 
     At step  512 , migration module  314  may write the data responsive to the read request to storage resource  310   b.  This step may reduce the number of data transfers over the network during migration, and future reads of the same data may be satisfied from storage resource  310   b.    
     At step  514 , migration module  314  may update bitmap  320  to indicate blocks of data that have been written to storage resource  310   b . After completion of step  514 , method  500  may end. 
     At step  516 , in response to a determination that the data associated with the read request has been migrated to destination storage resource  310   b , destination storage resource  310   b  may communicate (e.g., to host  302 ) the data responsive to the read request. After completion of step  516 , method  500  may end. 
     Although  FIG. 5  discloses a particular number of steps to be taken with respect to method  500 , method  500  may be executed with greater or lesser steps than those depicted in  FIG. 5 . In addition, although  FIG. 5  discloses a certain order of steps to be taken with respect to method  500 , the steps comprising method  500  may be completed in any suitable order. In addition, steps  502 - 510  may be repeated, independently and/or collectively, as often as desired or required by a chosen implementation. 
     Method  500  may be implemented using system  300  or any other system operable to implement method  500 . In certain embodiments, method  500  may be implemented partially or fully in software and/or firmware embodied in computer-readable media. 
       FIG. 6  illustrates a flow chart of an example method  600  for performing a write request during migration of data, in accordance with certain embodiments of the present disclosure. According to one embodiment, method  600  preferably begins at step  602 . As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system  300 . As such, the preferred initialization point for method  600  and the order of the steps  602 - 606  comprising method  600  may depend on the implementation chosen. 
     At step  602 , storage array  308   b  may receive a write request (e.g., from host  302 ) for destination storage resource  310   b  while a migration operation (e.g., method  400 ) is taking place. 
     At step  604 , in response to the write request, storage array  308   b  may store data associated with the write request on destination storage resource  310   b.    
     At step  606 , in response to the write request, migration module  314  may update bitmap  320  to indicate blocks of data that have been written pursuant to the write operation. After completion of step  606 , method  600  may end. 
     Although  FIG. 6  discloses a particular number of steps to be taken with respect to method  600 , method  600  may be executed with greater or lesser steps than those depicted in  FIG. 6 . In addition, although  FIG. 6  discloses a certain order of steps to be taken with respect to method  600 , the steps comprising method  600  may be completed in any suitable order. In addition, steps  602 - 606  may be repeated, independently and/or collectively, as often as desired or required by a chosen implementation. 
     Method  600  may be implemented using system  300  or any other system operable to implement method  600 . In certain embodiments, method  600  may be implemented partially or fully in software and/or firmware embodied in computer-readable media. 
     In the discussion of methods  400 ,  500  and  600  above, many references are made to “read requests,” “read operations,” “write requests,” ad “write operations.” For the purposes of this disclosure, such terms are used to broadly refer to any suitable read or write operation that may be issued or communicated in accordance with any suitable storage technique, protocol, and/or standard (e.g., Small Computer System Interface, Internet Small Computer System Interface, FibreChannel, etc.). 
     Using the methods and systems disclosed herein, problems associated with conventional approaches to data migration may be improved, reduced, or eliminated. For example, using the migration approaches set forth in this disclosure, migrated data and data stored pursuant to write operations may only be communicated over a network once, instead of twice as is the case with traditional approaches. In addition, host connections to a storage network are migrated automatically from the destination storage array and no reconfiguration of a host or network may be required to allow a host to access the destination storage resource. 
     Although the present disclosure has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and the scope of the disclosure as defined by the appended claims.