JP2015090631A - Storage control device, storage system, storage control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute a load between controllers, and equalize an access performance between storage devices.SOLUTION: A storage control device including a plurality of controllers receiving a request of a host computer and implementing an input/output of an allocated storage device comprises: grouping means; and path control means. The grouping means is configured to divide the storage devices in a pool to groups of the number of controllers. The path control means is configured to; allocate one group to a master controller of the pool; allocate other groups to other controller in which access to storage devices in the pool is slower than the master controller of the pool; and cyclically change the group to be allocated to the master controller of the pool for each prescribed time.

Description

  The present invention relates to a storage control device, a storage system, a storage control method, and a program, and more particularly to load distribution among a plurality of access controllers.

  Patent Document 1 discloses a storage device connected from an information processing apparatus through a plurality of logical paths. This system refers to the response time to determine the load on the logical path, and determines the logical path to which the data input / output request is assigned according to the load.

  Patent Document 2 discloses a system in which a plurality of host computers and a plurality of logical volumes are connected via a network. The plurality of logical volumes are managed by being divided into a plurality of array groups. When there is a difference in access frequency between array groups, this system migrates data of a logical volume of a frequent group to a logical volume of a less frequent group.

  Patent Document 3 discloses a system in which a plurality of server computers and a plurality of logical disks LU are connected by a plurality of paths. In this system, paths that pass through the same channel adapter are managed in groups, and when a delay occurs in a certain path, the path is blocked in units of groups.

JP 2005-10956 A JP 2012-108931 JP JP 2011-238290 A

  The technique of Patent Document 1 cannot be applied to a system having an ALUA (Asymmetric Logical Unit Access) configuration. In the ALUA configuration, when accessing a storage device, the performance varies depending on the path through which it passes. Therefore, in the ALUA configuration, when the technique of Patent Document 3 is applied, access concentrates only on paths with good performance. Patent documents 2 and 3 do not solve the above problems.

  The present invention aims to solve the above problems.

  A storage control device according to an embodiment of the present invention is connected to a pool including a plurality of storage devices and a host computer, receives a request from the host computer, and executes input / output of the allocated storage device A plurality of storage control devices, grouping means for dividing the storage devices in the pool into groups of the number of controllers, assigning one group to the master controller of the pool, and assigning other groups to the pool in the pool Path control means for assigning to another controller that is slower than the master controller of the pool and accessing the storage device and cyclically changing a group to be assigned to the master controller of the pool every predetermined time.

  A storage control method according to an embodiment of the present invention is a method in a storage device that is connected to a pool of a plurality of storage devices and includes a plurality of controllers, and the storage devices in the pool are assigned the number of controllers. Divide into groups, assign one group to the master controller of the pool (note: Optimized path setting), and assign other groups to other controllers whose access to the storage device in the pool is slower than the master controller of the pool The group assigned to the master controller of the pool is cyclically changed every predetermined time, and an input / output request designating one of the storage devices is received from the host computer, and assigned to the designated storage device Access via controller.

  A program according to an embodiment of the present invention includes a plurality of controllers that are connected to a pool including a plurality of storage devices and a host computer, receive a request from the host computer, and execute input / output of the allocated storage device A grouping process that divides the storage devices in the pool into groups of the number of controllers, assigns one group to the master controller of the pool, and accesses other storage groups to the storage devices in the pool. Is assigned to another controller that is later than the master controller of the pool, and a path control process is executed for cyclically changing the group to be assigned to the master controller of the pool every predetermined time.

  In a control device that is connected between a host computer and a storage device and includes a plurality of controllers with different access performance corresponding to the storage device, the load between the controllers is distributed and the access performance between the storage devices is equalized. Can do.

FIG. 1 is a configuration diagram of a storage control apparatus 100 as an example of the first embodiment. FIG. 2 is a configuration diagram of an LU management table that is a part of the management table 111. FIG. 3 is a configuration diagram of an LU controller table that is a part of the management table 111. FIG. 4 shows an access state performed when the LU controller table is in the state shown in FIG. FIG. 5 is a configuration diagram of the LU controller table after replacement. FIG. 6 shows an access state performed when the LU controller table is in the state shown in FIG. FIG. 7 is an operation flowchart of the grouping unit 110. FIG. 8 is an operation flowchart of controller assignment and change for the LU of the path control unit 112. FIG. 9 shows the configuration of the LU management table of the second embodiment. FIG. 10 shows controller assignments in the second embodiment. FIG. 11 shows a change after a predetermined time of controller assignment in the second embodiment. FIG. 12 is a configuration diagram of the storage control apparatus 100 as an example of the third embodiment.

  In recent years, virtualization of hosts and storage has progressed, and a large number of virtual hosts are connected to the storage, and a large number of virtual disks are built in the storage and used flexibly by using as many as necessary. The system has become commonplace. Normally, the logical disk access from the host to the storage apparatus is connected to a plurality of controllers for redundancy, and the logical disk is accessed through one of the controllers in the normal state. In the case of a storage device configured to have different access performance for each logical disk depending on the controller connected at this time, there may be a concentration of load on the controller where the performance occurs or access performance may be biased for each host was there. A storage control apparatus 100 for solving such problems will be described.

(Configuration of the first embodiment)
FIG. 1 is a configuration diagram of a storage control apparatus 100 as an example of the present embodiment. The controller 101-1 (controller 0) and the controller 101-2 (controller 1) of the storage control apparatus 100 of this example are respectively a host computer 201 (host 1), a host computer 202 (host 2), and a host computer 203 (host). m) connected to the host computer 204 (host n). Furthermore, the controller 0 and the controller 1 are each connected to the physical disk group 105.

  Note that the host 201 and the like and the physical disk group 105 connected to the storage control device 100 constitute a storage system 300 as a whole.

  The physical disk group 105 includes a plurality of LUs (Logical Units) that are logical disk devices. The LU is mapped to a physical disk by the controller, for example, when accessed. Each host accesses one LU via one of a plurality of redundant controllers. At this time, for example, the host 1 can access the LU through either the controller 0 or the controller 1, but the access performance differs depending on the path through each LU. Such a configuration is called an ALUA configuration.

  The storage control apparatus 100 having the ALUA configuration can perform path switching control between the host and the LU by a SCSI (Small Computer System Interface) command for controlling the ALUA. A path that is optimal for access for each LU, that is, a path with excellent access performance is called an Active / Optimized path, and other paths are called Active / Non-Optimized paths. The controller notifies the host of which controller passes through the Active / Optimized path according to the specification of Report Target Port Groups of the SCSI command for ALUA control.

  The storage control device 100 manages, as a pool, a collection of physical disks, for example, in units of RAID (Redundant Arrays of Independent Disks). The controller that controls the pool is any controller in the storage control apparatus 100, and this controller is referred to as a pool master controller. In FIG. 1, two pools, pool 0 and pool 1, are connected to the storage control device 100. The master controller of pool 0 is controller 0, and the master controller of pool 1 is controller 1.

  Access to a pool is always made from the master controller of the pool. When an access request for an LU is issued to the master controller of the LU, the master controller directly accesses the LU. If an access request for an LU is issued to a controller (non-master controller) other than the master controller of the LU, the non-master controller, for example, transfers the access request to the master controller and indirectly assigns the LU. to access.

  Each controller includes a grouping unit 110, an LU management table, a path control unit 112, and an I / O control unit 113. The grouping unit 110, the path control unit 112, and the I / O control unit 113 are electronic logic circuits built in the controller. The grouping unit 110, the path control unit 112, and the I / O control unit 113 are realized by a controller processor (not shown) executing a program stored in a control memory (not shown) in the controller. May be. In this case, the controller is a kind of computer. The LU management table is stored in the control memory in the controller.

  The grouping unit 110, the LU management table, and the path control unit 112 may be realized by an electronic logic circuit and a control memory in the storage control device 100, separately from the controller. Further, the grouping unit 110 and the path control unit 112 are realized by executing a program stored in a control memory (not shown) in the storage control device 100 by a processor (not shown) of the storage control device 100. May be. In this case, the storage control device 100 is a kind of computer.

  FIG. 2 is a configuration diagram of an LU management table that is a part of the management table 111. The LU management table has an area for storing the number of accesses and the group number for each LU. This figure shows that the storage control apparatus 100 is connected with two pools each including four LUs. In this figure, for example, pool 0 includes LUs with LUNs (Logical Unit Numbers) of 0 to 3, each of which has an access number of 20, 30, 30, 20, and LUNs with LUNs of 0 and 1. This shows that group 0 and LUN are divided into two groups, group 1 of LUs 2 and 3. This LU management table may be distributed and stored in different controllers for each pool.

  FIG. 3 is a configuration diagram of an LU controller table that is a part of the management table 111. The LU controller table has an area for storing controller identification information used in the Active / Optimized path for each LU. In this example of the LU management table of FIG. 2, for example, for an LU belonging to group 0 (LUN is 0, 1), controller 0 is used in the Active / Optimized path and LU belonging to group 1 is shown. (LUN is 2 or 3) indicates that the controller 1 is used in the Active / Optimized path. The same LU controller table may be stored in all controllers.

  The I / O control unit 113 receives the input / output request transmitted by the host, and accesses the physical disk corresponding to the LU specified by the request. In addition, the I / O control unit 113 counts the number of accesses to the LU that has been accessed in the area for storing the number of accesses in the management table 102.

  The grouping unit 110 refers to the number of accesses to the LU management table at regular intervals, groups the pool so that the total number of accesses to each LU is as uniform as possible, and records the number in the group number area of the LU management table. To do. Here, equality is not a strict meaning, but means that the difference in the number of accesses between groups is below a predetermined condition. FIG. 7 is an operation flowchart of the grouping unit 110. In this example, the difference in the number of accesses between groups is equal to or less than the maximum access number LU. The index for grouping is not limited to the number of accesses, and may be the amount of transfer data or the I / O busy time ratio.

  The path control unit 112 determines a controller to be used as an Active / Optimized path for each LU group. This is called assigning a group to a controller or assigning a controller to a group. For each LU, the path control unit 112 records the assigned controller identifier in the identification information area of the controller used in the Active / Optimized path of the LU controller table.

  Upon receiving the Report Target Port Groups command issued by the host, the path control unit 112 obtains the controller identification information corresponding to the LU specified by the command from the LU controller table and outputs it to the host. The LU is accessed via the controller.

  FIG. 4 shows an access state performed when the LU controller table is in the state shown in FIG. LUN0 is accessed via controller 0, and LUN2 is accessed via controller 1.

  Note that the path control unit 112 replaces the controllers of Active / Optimized paths between groups at regular time intervals.

  FIG. 5 is a configuration diagram of the LU controller table after replacement. In this example of the LU management table in FIG. 2, the controller used in the Active / Optimized path is changed from 0 to 1 for the LU belonging to group 0 (LUN is 0, 1). For LUs belonging to 1 (LUNs 2 and 3), the controller used in the Active / Optimized path is changed from 1 to 0.

  FIG. 6 shows an access state performed when the LU controller table is in the state shown in FIG. LUN 0 is accessed via the controller 1 and LUN 2 is accessed via the controller 0.

  FIG. 8 is an operation flowchart of controller assignment and change for the LU of the path control unit 112.

  When the grouping unit 110, the management table 111, and the path control unit 112 are provided inside the controller, each unit performs the above-described operation with respect to the pool in which the controller is the master controller. In this case, when the information in the LU controller table is set or changed, the path control unit 112 may transmit the setting / change information to another controller.

  The storage control device 100 according to the present embodiment can distribute the load between controllers and equalize access performance between storage devices in an ALUA configuration. The reason is that the bus control unit 112 changes the assignment of the controller to the group into which the pool is divided. This is because the access to the LU in the pool is not always connected to the controller on the pool master side. Further, the grouping unit 110 divides the pool into groups with equal access amounts.

  In this embodiment, the storage controller 100 includes two controllers and the number of LU pools to be connected is not limited to two. When the number of controllers and pools is N equal to or greater than 3, the grouping unit 110 divides each pool into N and assigns the N groups to the master controller in round robin.

(Second Embodiment)
When the path is evenly allocated by the number of accesses by the grouping unit 110 as in the first embodiment, an active / optimized path is also provided to a controller that is not a pool master without exception for a core business LU that always requires access performance. There will be a period of allocation. In this case, there arises a problem that even if the load in the storage is uniform, the entire system becomes slow.

  As a countermeasure, in the storage control device 100 of the present embodiment, an area in which a priority flag can be set is provided in the management table, and the user sets a priority flag to an LU that always requires access performance from the maintenance terminal or management software.

  FIG. 9 shows the configuration of the LU management table of the present embodiment. In this figure, priority flags are set for LUs with LUNs 0 and 2 in pool 0. The grouping unit 110 sets the priority group 100 for the LU for which the priority flag is set, and divides the group so that the number of accesses is equal for the other LUs. The example of FIG. 9 shows that the pool 0 is divided into two groups: an LU group 0 with an LUN of 1 and an LU group 1 with an LUN of 3. As described above, for the pool 1 in which the priority flag is not set, grouping is executed with the same logic as in the first embodiment.

  The path control unit 112 sets the Active / Optimized path of the priority group 100 to be a pool master without fail, and distributes the Active / Optimized of other groups to each controller. FIG. 10 shows controller assignment in the present embodiment. FIG. 11 shows a change after a predetermined time of controller assignment in the present embodiment.

  In FIG. 10, the priority group 100 is assigned to the controller 0 that is the pool master of the pool 0. In the pool 0, the LU of the group 0 (LUN = 1) is initially assigned to the controller 1 and the LU of the group 1 (LUN = 3) is assigned to the controller 0.

  After a certain time, in the pool 0, the allocation controller of the LU of the group 0 (LUN = 1) and the LU of the group 1 (LUN = 3) is changed and reversed, but the LU of the group 100 is fixed. Assigned to the controller 0.

  As is clear from FIGS. 9 to 11, in the present embodiment, a pool without a priority flag (for example, pool 1 in the figure) is handled in the same manner as in the first embodiment. The

  The storage control device 100 of this embodiment guarantees the stability of the access performance of the entire system. This is because the path control unit 112 assigns an LU that requires performance to a controller that is a pool master in a fixed manner.

(Third embodiment)
FIG. 12 is a configuration diagram of the storage control apparatus 100 as an example of the present embodiment. The storage control device 100 includes a plurality of controllers 101, a grouping 110, and a path control unit 112.

  The controller 101 is connected to a pool including a plurality of storage devices and a host computer, receives a request from the host computer, and executes input / output of the allocated storage device.

  The grouping unit 110 divides the storage devices in the pool into groups corresponding to the number of controllers. The path control unit 112 assigns one group to the master controller of the pool, assigns another group to another controller whose access to the storage device in the pool is slower than the master controller of the pool, and every predetermined time, The group assigned to the master controller of the pool is changed cyclically.

  The storage control device 100 according to the present embodiment can distribute the load between controllers and equalize access performance between storage devices in an ALUA configuration. The reason is that the bus control unit 112 changes the assignment of the controller to the group into which the pool is divided. This is because the access to the LU in the pool is not always connected to the controller on the pool master side.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

100 storage controller
101 controller
105 physical disks
110 Grouping part
111 Management table
112 Path control unit
113 I / O controller
201, 202, 203, 204 Host computer

Claims (9)

A storage control device comprising a plurality of controllers connected to a pool including a plurality of storage devices and a host computer, receiving a request from the host computer, and executing input / output of the allocated storage device,
Grouping means for dividing the storage devices in the pool into groups of the number of controllers;
One group is assigned to the master controller of the pool, and another group is assigned to another controller whose access to the storage device in the pool is slower than the master controller of the pool. And a path control means for cyclically changing a group to be allocated to the storage control apparatus.   The storage control device according to claim 1, wherein the grouping unit refers to an input / output amount for each storage device and divides the input / output amount between the groups into groups so that a difference between the groups is equal to or less than a predetermined condition.   The storage control unit according to claim 1 or 2, wherein the grouping unit allocates the storage device in the pool to which a priority attribute is assigned to a master controller of the pool.   4. The storage control device according to claim 1, wherein the storage control device is connected to the same number of pools as the plurality of controllers, and each of the plurality of controllers is any one of the plurality of pools. The storage control device according to any one of claims 1 to 4,
A pool of the plurality of storage devices;
A storage system including the host computer. A method for a storage device connected to a pool of a plurality of storage devices and comprising a plurality of controllers,
Dividing the storage devices in the pool into groups of the number of controllers;
Assign one group to the master controller of the pool (note: Optimized path setting), assign the other group to another controller whose access to the storage device in the pool is slower than the master controller of the pool,
The group assigned to the master controller of the pool is changed cyclically at a predetermined time,
A storage control method for receiving an input / output request designating one of the storage devices from a host computer and accessing the designated storage device via a controller assigned thereto.   The storage control method according to claim 6, wherein the input / output amount for each storage device is measured and divided into groups such that the difference between the groups in the input / output amount is equal to or less than a predetermined condition.   The storage control means according to claim 6 or 7, wherein the storage device in the pool to which the priority attribute is assigned is assigned to a master controller of the pool. A computer including a plurality of controllers connected to a pool including a plurality of storage devices and a host computer, receiving a request from the host computer, and executing input / output of the allocated storage device,
A grouping process for dividing the storage devices in the pool into groups of the number of controllers;
One group is assigned to the master controller of the pool, and another group is assigned to another controller whose access to the storage device in the pool is slower than the master controller of the pool. And a path control process for cyclically changing a group to be assigned to the program.

Images