Abstract:
In one embodiment, a storage controller comprises a first I/O port that provides an interface to a host computer, a second I/O port that provides an interface to a storage device, a processor that receives I/O requests generated by the host computer and, in response to the I/O requests, generates and transmits I/O requests to the storage device, and a memory module communicatively connected to the processor. The memory module comprises logic instructions which, when executed by the processor, configure the processor to collect performance data and availability data for a plurality of logical devices (LDEVS) managed by the storage controller, and present the performance data and availability data to a reporting interface.

Description:
BACKGROUND  
       [0001]     The described subject matter relates to data storage in electronic computing, and more particularly to intelligent logical unit provisioning.  
         [0002]     Effective collection, management, and control of information have become a central component of modern business processes. To this end, many businesses, both large and small, now implement computer-based information management systems.  
         [0003]     Data management is an important component of computer-based information management systems. Many users implement storage networks to manage data operations in computer-based information management systems. Storage networks have evolved in computing power and complexity to provide highly reliable, managed storage solutions that may be distributed across a wide geographic area, and across physical storage devices that are under the management of a storage controller (i.e., internal) or outside the management of a storage controller (i.e., external).  
         [0004]     Adroit management of storage network resources contributes to the effective management of storage networks. Existing management interfaces provide limited information for managing storage resources. Management interfaces that provide additional management information would be useful.  
       SUMMARY  
       [0005]     In one embodiment, a storage controller comprises a first I/O port that provides an interface to a host computer, a second I/O port that provides an interface a storage device, a processor that receives I/O requests generated by the host computer and, in response to the I/O requests, generates and transmits I/O requests to the storage device, and a memory module communicatively connected to the processor. The memory module comprises logic instructions which, when executed by the processor, configure the processor to collect performance data and availability data for a plurality of logical devices (LDEVS) managed by the storage controller, and present the performance data and availability data to a reporting interface.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a schematic illustration of one embodiment of a storage network environment.  
         [0007]      FIG. 2  is a schematic illustration of one embodiment of an array controller.  
         [0008]      FIG. 3  is a flowchart illustrating operations in one embodiment of a method for intelligent logical unit provisioning  
         [0009]      FIG. 4  is a schematic illustration of one embodiment of a user interface for intelligent logical unit provisioning.  
     
    
     DETAILED DESCRIPTION  
       [0010]     Described herein are exemplary systems and methods for intelligent logical unit provisioning in a storage device, array, or network. The methods described herein may be embodied as logic instructions on a computer-readable medium. When executed on a processor such as, e.g., an array controller, the logic instructions cause the processor to be programmed as a special-purpose machine that implements the described methods. The processor, when configured by the logic instructions to execute the methods recited herein, constitutes structure for performing the described methods. The methods will be explained with reference to one or more logical volumes in a storage system, but the methods need not be limited to logical volumes. The methods are equally applicable to storage systems that map to physical storage, rather than logical storage.  
         [0011]      FIG. 1  is a schematic illustration of an exemplary implementation of a networked computing environment  100 . Referring to  FIG. 1 , computing environment  100  includes a storage pool  110  that provides data storage services to one or more computing devices. Storage pool  110  may be implemented in one or more networked storage cells  140 A,  140 B,  140 C. Exemplary storage cells include the STORAGEWORKS line of storage devices commercially available from Hewlett-Packard Corporation of Palo Alto, Calif., USA. Storage cells  140 A,  140 B,  140 C may be co-located or may be geographically distributed, and may be connected by a suitable communication network. The communication network may be embodied as a private, dedicated network such as, e.g., a Fibre Channel (FC) switching fabric. Alternatively, portions of communication network may be implemented using public communication networks pursuant to a suitable communication protocol such as, e.g., the Internet Small Computer Serial Interface (iSCSI) protocol. The number of storage cells  140 A,  140 B,  140 C that can be included in any storage network is limited primarily by the connectivity implemented in the communication network. For example, a switching fabric comprising a single FC switch can interconnect 256 or more ports, providing a possibility of hundreds of storage cells in a single storage network.  
         [0012]     Computing environment  100  further includes one or more host computing devices which utilize storage services provided by the storage pool  110  on their own behalf or on behalf of other client computing or data processing systems or devices. Client computing devices such as client  126  access storage the storage pool  110  embodied by storage cells  140 A,  140 B,  140 C through a host computer. For example, client computer  126  may access storage pool  110  via a host such as server  124 . Server  124  may provide file services to client  126 , and may provide other services such as transaction processing services, email services, etc. Host computer  122  may also utilize storage services provided by storage pool  110  on its own behalf. Clients such as clients  132 ,  134  may be connected to host computer  128  directly, or via a network  130  such as a Local Area Network (LAN) or a Wide Area Network (WAN).  
         [0013]      FIG. 2  is a schematic illustration of an exemplary embodiment of a storage cell  200 . Storage cell  200  may correspond to one of the storage cells  140 A,  140 B,  140 C depicted in  FIG. 1 . It will be appreciated that the storage cell  200  depicted in  FIG. 2  is merely one exemplary embodiment, which is provided for purposes of explanation.  
         [0014]     Referring to  FIG. 2 , storage cell  200  includes two Network Storage Controllers (NSCs), also referred to as “disk array controllers” or just “array controllers”  210   a ,  210   b  to manage operations and the transfer of data to and from one or more sets of disk drives  240 ,  242 . Array controllers  210   a ,  210   b  may be implemented as plug-in cards having a microprocessor  216   a ,  216   b , and memory  218   a ,  218   b . Each array controller  210   a ,  210   b  includes dual host adapter ports  212   a ,  214   a ,  212   b ,  214   b  that provide an interface to a host, i.e., through a communication network such as a switching fabric. In a Fibre Channel implementation, host adapter ports  212   a ,  212   b ,  214   a ,  214   b  may be implemented as FC N_Ports. Each host adapter port  212   a ,  212   b ,  214   a ,  214   b  manages the login and interface with a switching fabric, and is assigned a fabric-unique port ID in the login process. The architecture illustrated in  FIG. 2  provides a fully-redundant storage cell. This redundancy is entirely optional; only a single array controller is required to implement a storage cell.  
         [0015]     Each array controller  210   a ,  210   b  further includes a communication port  228   a ,  228   b  that enables a communication connection  238  between the array controllers  210   a ,  210   b . The communication connection  238  may be implemented as a FC point-to-point connection, or pursuant to any other suitable communication protocol.  
         [0016]     In an exemplary implementation, array controllers  210   a ,  210   b  further include a plurality of Fiber Channel Arbitrated Loop (FCAL) ports  220   a - 226   a ,  220   b - 226   b  that implements an FCAL communication connection with a plurality of storage devices, e.g., sets of disk drives  240 ,  242 . While the illustrated embodiment implement FCAL connections with the sets of disk drives  240 ,  242 , it will be understood that the communication connection with sets of disk drives  240 ,  242  may be implemented using other communication protocols. For example, rather than an FCAL configuration, a FC switching fabric may be used.  
         [0017]     In operation, the storage capacity provided by the sets of disk drives  240 ,  242  may be added to the storage pool  110 . When an application requires storage capacity, logic instructions on a host computer such as host computer  128  establish a LUN from storage capacity available on the sets of disk drives  240 ,  242  available in one or more storage sites. It will be appreciated that, because a LUN is a logical unit, not a physical unit, the physical storage space that constitutes the LUN may be distributed across multiple storage cells. Data for the application may be stored on one or more LUNs in the storage network. An application that needs to access the data queries a host computer, which retrieves the data from the LUN and forwards the data to the application.  
         [0018]     In operation, a user, administrator, or software module responsible for managing the storage pool  110  may periodically need to provision a new logical unit, such as logical unit  112   a ,  112   b , in the storage pool  110 .  FIG. 3  is a flowchart illustrating operations in one embodiment of a method for intelligent logical unit provisioning, and  FIG. 4  is a schematic illustration of one embodiment of a user interface for intelligent logical unit provisioning. The operations of  FIG. 3  may be implemented in a storage controller such as one of the storage controllers  210   a ,  210   b  to enable the storage controller to collect performance data and availability data from internal logical units (i.e., logical units defined from physical storage media within the storage cell) and external logical units (i.e., logical units defined from physical storage media outside the storage cell. Once collected, the performance data and availability data may be presented to a reporting interface, which may organize the data and present the data in a suitable interface.  
         [0019]     Referring to  FIG. 3 , at operation  310  a logical device is selected. In one embodiment, a logical device may correspond to a logical unit such as logical units  112   a ,  112   b , managed by the storage controller. At operation  315  a performance test is initiated on the logical device selected in operation  310 . In one embodiment, the storage controller initiates an online transaction performance (OLTP) test in which 8 KB blocks of data are written to and read from the logical unit for a predetermined time period such as, e.g., 250 ms. In one embodiment, the performance test implements a 60:40 ratio of read operations to write operations, although other ratios may be implemented. One technique for estimating the performance of an OLTP application may be accomplished by subjecting a storage unit to a workload including the following attributes: Block-size: 8 kB, access pattern: Random, read percentage 60%, write percentage: 40%, queue depth:  1  to n, where in causes an average response time of 30 ms. The general metric of concern is the maximum number of input/output operations per second (10/sec) that the storage unit can support. This information permits proper matching of application users and storage resources to maintain an acceptable performance experience for the application. One technique for measuring such performance, may include supplying the storage with a predetermined workload for a defined amount of time. The performance rate may be calculated by dividing the number of I/O operations completed by the time (e.g., in seconds) to give a result in units of I/O operations per second.  
         [0020]     At operation  320  a data warehouse test is initiated on the logical device selected in operation  310 . In one embodiment, the storage controller initiates a simulated data warehouse workload test in which 64 KB blocks of data are read sequentially from the logical unit for a predetermined time period such as, e.g., 250 ms. In alternate embodiments, different data block sizes may be read. One technique for estimating the performance of a data warehouse application may be accomplished by subjecting a storage unit to a workload consisting of the following attributes: Block-size: 64 KB, access pattern: Sequential, read percentage 100%, queue depth: 1 to n (where in causes an limited increase in MB/sec throughput as compared to n-1). A point of interest is to determine a maximum MB/sec that a configuration can sustain. Knowing these limits allows for successful sizing of the storage resources to be able to meet the high throughput demands from the application. In one embodiment, a performance rate may be calculated by the following formula: MB/sec=(((C*B))/1000000)/s, where C is defined as the number of I/O operations completed, B is defined as the Block Size of each 1.0 in bytes, and s is defined as the duration of the measurement time in seconds.  
         [0021]     If, at operation  325 , the LDEV selected in operation  310  is an external LDEV, then control passes to operation  330 , and the minimum number of paths to each external disk in the LDEV and to the array controller managing the LDEV is determined. This number is relevant in that a value of less than two represents storage which would not be considered as highly available. This number may be entered into the data table by the user at the time of external storage configuration. In one embodiment, a criteria for high availability is that no single point of failure causes data in the storage system to be inaccessible. So, a goal for a high availability configuration is to allow a user to have access to data stored in the storage product. Although a storage unit may be accessed through different paths, it is common that only a single path will be utilized at any particular point in time. One goal for high availability is not usually associated with general performance and has a different type of testing techniques which often includes such things as: 1) interface cable failures, 2) servers to be power-cycled during operation, and 3) disks failure. These types of failures are easily accomplished by physically removing an interface cable or disk and by turning off a server during a data integrity test. The testing philosophy for validating a high availability solution may focus on data integrity, where data is written and later read and checked to see if the retrieved data matches that which has been previously written. Storage performance, during this type of test, may not be related to a pass or fail criteria because the computer doing the test may be busy doing other tasks other than strict  10  performance on the storage.  
         [0022]     By contrast, if at operation  325  the LDEV selected in operation  310  is an internal LDEV, then control passes to operation  335  and the minimum number of paths to each internal disk and array controller is determined. For example, in the embodiment depicted in  FIG. 2 , there are two paths to each disk and to the array controllers that manage the LDEVs. The industry default for all internal disks would tend to be two paths, to provide redundancy. By contrast the number of paths to external storage can vary widely.  
         [0023]     At operation  340  characteristics of the array controller managing and the disk array housing the LDEV selected in operation  310  are collected. In one embodiment, the storage controller determines the RAID level implemented in the LDEV, the RAID group with which the LDEV is associated, the size of the LDEV, and the size and type of the disk(s) housing the LDEV. In one embodiment, the storage controller maintains these characteristics in a data table established when LDEV is created. In this embodiment, the storage controller can retrieve these characteristics from the data table.  
         [0024]     At operation  345  the results of the OLTP test initiated in operation  315  and the data warehouse test initiated in operation  320 , the path information collected in operations  330 ,  335 , and the characteristics collected in operation  345  are recorded in a suitable memory module. In one embodiment, the information collected in  FIG. 3  may be stored in a memory table such as the memory table  400  depicted in  FIG. 4 . Referring to  FIG. 4 , the data table  400  includes a column  405  that includes an identifier for the LDEV, a column  410  that identifies the RAID type associated with the LDEV, a column  415  that identifies the RAID group with which the LDEV is associated, a column  420  that identifies the size of the LDEV, a column  425  that identifies the disk type and size, a column  430  that identifies whether the LDEV is internal or external, a column  435  that includes the results of the OLTP performance test, a column  440  that includes the results of the data warehouse test, a column  445  that includes the minimum number of physical paths to the disks, and a column  450  that includes the minimum number of physical paths to the controller.  
         [0025]     Referring back to  FIG. 3 , at operation  350  the information in the memory table  400  may be forwarded to a reporting interface. In one embodiment, the reporting interface may include a user interface that presents the information to a user, e.g., on a suitable display. The user interface may further include logic instruction that permit a user to sort the data using one or more columns as a key. A user such as, e.g., a network administrator, may consult this information to make an informed judgment about which disk group(s) are good selections for provisioning a new LDEV as a host viewable logical unit (LU). Alternatively, the information in memory table  400  may be input to a software module that provisions LDEVs as host viewable LUs.  
         [0026]     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.  
         [0027]     Thus, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter.