JP6809797B2 - Storage device control device, storage device control method, and storage device control program - Google Patents

Description

The present invention relates to a control device of a storage device, a control method of the storage device, and a control program of the storage device, and more particularly to control and management of a connection path of a disk array device.

There is a disk array device that includes a plurality of storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive) to form an array. In such a disk array device, the physical area of the array is divided into fixed sizes called extents (physical extents) and managed, and the physical extents are virtually allocated at the time of write access to the logical volume. Physical extent allocation is triggered by writing (data writing) from the host device.

FIG. 11 is a diagram showing an image of physical extent allocation. Further, the unnecessary physical extents are released by a release command from the host device (for example, a SCSI (Small Computer System Interface) command UNMAP command (unmap command)).

Patent Document 1 relates to reducing the power consumption of a cluster type storage device, and when the number of accesses to a disk device is out of a predetermined threshold value, the storage controller that controls access to data of a logical volume may be changed. Proposed. For example, it has been proposed to stop one storage controller, change the storage controller, and change the active path of the logical volume when the number of accesses to the disk device is small.

Japanese Unexamined Patent Publication No. 2014-13459

However, the storage device of Patent Document 1 described above cannot cope with the case where a plurality of virtual machines exist on one logical disk.

An object of the present invention is a storage device control device, a storage device control method, and a storage device control program that can manage the optimum path of a storage device even when a plurality of virtual machines exist on one logical disk. Is to provide.

In order to achieve the above object, the control device of the storage device according to the present invention has an extent management table that manages a host identifier and a master controller for each extent, and the above-mentioned for each extent according to the access from the virtual machine. It includes a master switching control means for switching a controller to be a master.

The storage device control method according to the present invention holds a host identifier and a master controller association for each extent, and a controller that becomes the master for each extent based on the association according to access from a virtual machine. To switch.

The control program of the storage device according to the present invention refers to the reference process for referring to the host identifier and the extent management table that manages the master controller for each extent, and for each of the above extents according to the access from the virtual machine. The master switching process for switching the controller to be the master is executed.

According to the present invention, it is possible to manage the optimum path of the storage device even when a plurality of virtual machines exist on one logical disk.

(A) is a block diagram for explaining a control device according to an embodiment of the highest-level concept of the present invention, and (b) is a block diagram for explaining a disk array device using the control device of (a). is there. It is a block diagram for demonstrating the structure of the system using the disk array apparatus by one Embodiment of this invention. It is a figure which shows an example of the extent management table of one Embodiment of this invention. It is a flowchart for demonstrating the process at the time of storing VM data in LD in the disk array apparatus by one Embodiment of this invention. It is a figure which shows an example of the extent management table of one Embodiment of this invention. It is a block diagram for demonstrating the movement of the virtual machine of the disk array apparatus by one Embodiment of this invention. It is a flowchart for demonstrating the process at the time of moving a VM between host devices in the disk array device by one Embodiment of this invention. It is a figure which shows an example of the extent management table of one Embodiment of this invention. It is a figure which shows an example of the extent management table of one Embodiment of this invention. (A) is a block diagram for explaining a control device according to another embodiment of the present invention, and (b) is a flowchart for explaining a process by the control device of (a). It is a block diagram for demonstrating an example of the system including a disk array apparatus and a host apparatus. It is a block diagram for demonstrating the optimum path to a logical disk. It is a block diagram for demonstrating the movement of a virtual machine from a host device to another host device. It is a block diagram for explaining the movement of a virtual machine and the optimum path to a logical disk. It is a block diagram for explaining the movement of a virtual machine and the optimum path to a logical disk.

Before explaining the preferred embodiment of the present invention, the background technology will be described with reference to the drawings.

In a disk array device that has multiple storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive) and constitutes an array, the physical area of the array is managed by dividing it into fixed sizes called extents (physical extents). To do. Then, at the time of write access, the physical extent is virtually allocated to form a logical volume (LD: Logical Drive) (FIG. 11).

For each of these LDs, the disk array device determines a controller that proactively writes and reads data for the purpose of load distribution and the like. Hereinafter, a controller that proactively writes / reads such data is referred to as a master controller or a master. Each physical disk constituting the disk array device and one master controller are connected to each other. The performance is superior when data writing / reading processing is performed by the master controller. Therefore, in the connection between the host and the disk array device, the path connected to the master controller of the LD to be accessed is the optimum path (FIG. 12). FIG. 12 shows a state in which the master of the first logical disk is the controller A and the master of the second logical disk is the controller B.

Information acquisition / switching of the optimum path is possible by using a function called AULA (Asymmetric Logical Unit Access), which is specified as a standard function of SCSI-3. The host device can acquire the optimum path information by issuing the optimum path information acquisition command (REPORT TARGET PORT GROUPS) defined by the ALUA function to the disk array device. When the optimum path is changed, the disk array device notifies the host device (Unit Attention), so that the host device reacquires the optimum path information from the disk array device (issues the REPORT TARGET PORT GROUPS command). Can be encouraged.

As the data stored in the LD, there may be data of a virtual machine that operates a plurality of virtual machines (VMs: Virtual Machines) on a physical server such as a virtual machine environment. Hereinafter, the virtual machine will be referred to as VM. As the data stored in the LD, there is also the data of the VM that operates the plurality of VMs, and the data of the plurality of VMs may be stored in one LD on the disk array device.

In a virtual machine environment, VMs are moved between virtual machine environments from one physical server to another for the purpose of failover in the event of maintenance or physical failure, load distribution, etc. Exists.

Here, consider a case where a plurality of VM data are stored in one LD and one VM is moved to another virtual machine environment (FIG. 13). In the disk array device, the master is determined for each LD, the master of a certain LD (first logical disk) is the controller A, and the VM1 and VM2 are operating on the host device a. The master of the LD (second logical disk) is the controller B, and the VM3 is operating on the host device b.

When a certain VM1 is moved to the host device b, the host device b is connected to the controller B and the master is the controller A, so that the VM1 is accessed from a non-optimal path (FIG. 14). Here, when the master of the VM1 is changed to the controller B, the VM1 is operated by the host device b, so that the access is from the optimum path. However, since the master is determined in LD units and the master of VM2 in which data is stored in the LD is controller A, VM2 is accessed from a non-optimal path (FIG. 15). That is, since either VM is always accessed from the non-optimal path, there is a problem that the master cannot be determined for each VM when a plurality of VM data are stored in one LD.

Next, the control device and the control method of the storage device according to the embodiment of the highest level concept of the present invention will be described. FIG. 1A is a block diagram for explaining a control device of a storage device according to an embodiment of the highest-level concept of the present invention, and FIG. 1B is a disk array using the control device of FIG. 1A. It is a block diagram for demonstrating an apparatus.

An example of the control device of the storage device of this embodiment is the controller 150 of FIG. 1A. The controller 150 of FIG. 1A includes a master switching control unit 151 as an example of the master switching control means, and an extent management table 152. The master switching control unit 151 switches the controller to be the master for each extent according to the access from the virtual machine (VM). The extent management table 152 manages a host identifier and a master controller for each extent. The disk array device 170 of FIG. 1 (b) includes the controller 150 of FIG. 1 (a) and the disk array 160.

According to the control device and the control method of the storage device of the present embodiment, the extent management table 152 manages the host identifier and the master controller for each extent. Then, the master switching control unit 151 switches the master for each extent according to the access from the VM. For example, when the VM moves to another host device, the master is switched. Even if the VM moves to another host device, it is possible to access the storage device from the optimum path for each VM. By enabling access from the optimum path for each VM, it is possible to reduce performance degradation. Hereinafter, more specific embodiments will be described in detail with reference to the drawings.

[One Embodiment]
The control device of the storage device and the control method of the storage device according to the embodiment of the present invention will be described. FIG. 2 is a block diagram for explaining a system configuration using a disk array device as an example of a storage device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of an extent management table according to an embodiment of the present invention. FIG. 4 is a flowchart for explaining a process when the VM data is stored in the LD in the disk array device according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of an extent management table according to an embodiment of the present invention. FIG. 6 is a block diagram for explaining the movement of the virtual machine of the disk array device according to the embodiment of the present invention. FIG. 7 is a flowchart for explaining the processing when the VM moves between the host devices in the disk array device according to the embodiment of the present invention. FIG. 8 is a diagram showing an example of an extent management table according to an embodiment of the present invention. FIG. 9 is a diagram showing an example of an extent management table according to an embodiment of the present invention.

With reference to FIG. 2, a disk array device 1 as an embodiment of the present invention is shown. In FIG. 2, the disk array device 1 includes a controller 2 and a disk unit 3 including a plurality of HDDs (Hard Disk Drives) 10 as an example of a plurality of storage devices. The plurality of storage devices may be SSDs (Solid State Drives), but the case of a plurality of HDDs 10 will be described below.

The controller 2 is connected to one or a plurality of host devices 21. The controller 2 has a host control unit 5 that sends and receives data to and from the host device 21, a disk control unit 6 that is connected to the disk unit 3 and reads and writes data to and from the HDD 10, an extent management table 30, and master switching control. It has means 40 and.

The host control unit 5 has an optimum path information return means 50 and an optimum path change notification means 51.

The host device 21 has a virtual machine environment 20, and a plurality of virtual machines (VMs) 22 are constructed on the virtual machine environment 20.

The disk array 80 having one RAID (Redundant Arrays of Inexpensive Disks or Redundant Arrays of Independent Disks) configuration of the disk unit 3 is composed of a plurality of HDDs 10 and forms a logical volume (LD). The data of VM22 is stored in the LD. The host device 21 and the VM 22 issue the optimum path information acquisition notification 25 to the disk array device 1 when the optimum path information is acquired. When the disk array device 1 receives the optimum path information acquisition notification 25, the disk array device 1 returns the corresponding optimum path information to the host device 21 and the VM 22 by the optimum path information return means 50. The host device 21 and the VM 22 that have acquired the optimum path information perform subsequent access via the acquired optimum path.

The master switching control means 40 of the controller 2 switches the controller 2 as a master for each logical extent in response to the access from the VM 22. When the master is switched, the optimum path change notification means 51 notifies the corresponding host device 21 and VM 22 of the change in the optimum path status. The host device 21 and the VM 22 notified of the change in the optimum path status acquire the optimum path information by issuing the optimum path information acquisition notification 25 to the disk array device 1 again.

Next, with reference to FIG. 3, the detailed configuration of the extent management table 30 of FIG. 2 is shown. In FIG. 3, the extent management table 30 has a table 31 for each LD. In FIG. 3, it is assumed that the table 31 of LD # 0 to LD # N is provided. Each table 31 manages the extent number 32, the host identifier 33, the master controller number 34, and the number of accesses 35 for each path. In FIG. 3, the access count 35 for each path is the pass # 0 access count to the pass # M access count. In other words, the extent management table 30 holds an association between the host identifier 33 and the master controller number 34 of the controller to be the master for each extent number 32 of the LD. Further, it can be said that the extent management table 30 holds an association of the host identifier 33, the master controller number 34 of the master controller, and the path access count 35 for each extent number 32 of the LD.

The host identifier 33 is registered when information for discriminating the VM 22 (eg, WWN (World Wide Name)) is managed and an extent is assigned by writing from the VM 22 to the LD.

The master controller number 34 stores the current master controller number, and the initial value is the master controller of the LD to which the extent belongs.

The path access count 35 is counted up for each access from the VM 22 for each path connected between the controller 2 and the host device 21.

The optimum path information acquisition notification 25, which is an ALUA function of the host device 21, the optimum path information return means 50 and the optimum path change notification means 51 of the host control unit 5 of the controller 2 of the disk array device 1 are well known to those skilled in the art. It is a configuration. Moreover, since these elements are not directly related to the features of the present invention, the detailed configuration thereof will be omitted.

(Explanation of operation)
Next, the operation of the disk array device 1 of FIG. 2 is shown in the flowcharts shown in FIGS. 4 and 7, the specific disk array device 1 shown in FIG. 6, and the specific extent management table shown in FIGS. 5, 8 and 9. 30 will be described.

As a specific example for explanation, it is assumed that the host device # 0 is connected to the controller # 0 (path # 0) and the host device # 1 is connected to the controller # 1 (path # 1). Further, it is assumed that VM # 1 and VM # 2 are operating on the host device # 0, and VM # 3 is operating on the host device # 1. It is assumed that the data of VM # 1 and VM # 2 is stored in LD # 0, the data of VM # 3 is stored in LD # 1, and the master controller of LD # 0 is the master controller of controller # 0 and LD # 1. Is controller # 1. The LD number, the controller number, the unit of the extent, the configuration of the host device, and the like show an example thereof, and the present invention is not limited to the above-mentioned values and methods.

(Processing when storing VM22 data in LD)
First, the process when the data of the VM 22 is stored in the LD will be described using the flowchart shown in FIG. 4 and the information of the specific extent management table 30 shown in FIG.

When the LD is accessed from the VM 22 on the host device 21 (FIG. 4, S101), the disk array device 1 acquires the host identifier 33 of the VM 22 (FIG. 4, S102). Next, the number of the access destination extent from the VM 22 is extracted (FIG. 4, S103), and it is checked whether or not the information of the corresponding extent number has been registered in the extent management table 30 of FIG. 5 (FIG. 4, S110).

When the extent information has been registered (YES in FIG. 4, S110), the corresponding path access count 35 in the extent management table 30 is counted up (FIG. 4, S113), and data is written / read (FIG. 4, S113). FIG. 4, S114).

When the extent information is not registered (NO in FIG. 4, S110), the registration of the host identifier 33 (FIG. 4, S111) and the registration of the master controller number 34 (FIG. 4, S112) are performed. After that, the corresponding path access count 35 is counted up (FIG. 4, S113), and data is written / read (FIG. 4, S114).

(Processing when the VM 22 moves between the host devices 21)
Next, the processing when the VM 22 moves between the host devices 21 (FIG. 6) will be described using the flowchart shown in FIG. 7 and the information in the specific extent management table 30 shown in FIGS. 8 and 9. ..

The master switching control means 40 of the controller 2 periodically checks the extent management table 30 for each LD (FIG. 7, S201), and further checks each logical extent (FIG. 7, S202). It is checked whether any of the path access counts 35 of the extent management table 30 exceeds the first threshold value (example: 110) (FIG. 7, S203). Specifically, it is checked whether any of the number of times of access to pass # 0 to the number of times of access to pass # 1 in FIG. 8 exceeds the first threshold value.

If the first threshold value is not exceeded (NO in FIG. 7, S203), the next target extent and LD are checked. In the case of VM # 1 in FIG. 8, since neither the pass # 0 access count to the pass # 1 access count exceeds the first threshold value, the next target extent and LD are checked.

When the first threshold value is exceeded (YES in FIG. 7, S203), the controller 2 to which the path corresponding to the path access count 35 exceeding the first threshold value is connected is different from the corresponding master controller number 34. Is checked (FIG. 7, S204). In FIG. 8, the number of pass # 1 accesses of VM # 2, VM # 3, and VM # 4 exceeds the first threshold value.

If the controller 2 to which the corresponding path is connected to the path access count 35 exceeding the first threshold value and the corresponding master controller number 34 are not different, the path access count 35 is cleared (FIG. 7, S208). Check the following target extents and LDs. Here, it is VM # 3 in FIG. 8 that the controller 2 to which the path corresponding to the path access count 35 exceeding the first threshold value is connected and the corresponding master controller number 34 match.

When the controller 2 to which the corresponding path is connected to the path access count 35 exceeding the first threshold value and the corresponding master controller number 34 are different (YES in FIG. 7, S204), the path access count 35 is checked. (FIG. 7, S205). That is, it is a check whether the number of pass accesses 35 of the path connected to the controller 2 corresponding to the current master controller number 34 is equal to or less than the second threshold value (example: 40). Here, the reason why the path access count 35 exceeds the first threshold value and the corresponding master controller number 34 is different from the controller 2 to which the path is connected is VM # 2 and VM # 4 in FIG. Is.

When the second threshold value is exceeded (NO in FIG. 7, S205), the pass access count 35 is cleared (FIG. 7, S208), and the next target extent and LD are checked. Here, it is VM # 4 in FIG. 8 that exceeds the second threshold value. In FIG. 8, since the number of pass # 0 accesses of VM # 4 exceeds the second threshold value, the number of pass access 35 of VM # 4 is cleared as shown in FIG. 9, and the next target extent and LD are checked.

When it is equal to or less than the second threshold value (YES in FIG. 7, S205), the master controller number 34 of the extent management table 30 is switched to the controller 2 to which the path corresponding to the path access count 35 exceeding the first threshold value is connected. (FIG. 7, S206). Further, after notifying the host device 21 of the corresponding path as the optimum path (FIG. 7, S207), the path access count 35 is cleared (FIG. 7, S208), and the next target extent and LD are checked. In FIG. 8, since the number of times of access to path # 0 of VM # 2 does not exceed the second threshold value, the path corresponding to the master controller number 34 of the extent management table 30 and the number of times of pass access 35 exceeding the first threshold value is Change to the connected controller 2. Further, after notifying the host device 21 of the corresponding path as the optimum path, the path access count 35 of VM # 2 is cleared as shown in FIG. 9, and the next target extent and LD are checked.

By the above operation, even when the VM22 is moved between the host devices 21, the extent master in which the VM22 data is stored can be changed to the controller 2 to which the destination host device 21 is connected. It can be accessed from VM22 with the optimum path.

(Explanation of effect)
As described above, according to the control device of the storage device and the control method of the storage device of the present embodiment, the performance deterioration can be reduced by enabling access from the optimum path for each VM22. Further, since the controller 2 to be the master is changed by referring to the information of the path access count 35 of the extent management table 30 and the information of the master controller number 34, it is possible to reduce the deterioration of the performance of the entire storage device.

[Other Embodiments]
The control device of the storage device and the control method of the storage device described above can also be realized by an information processing device capable of executing a program that realizes the above-described configuration and operation. This program may be distributed in the form of computer-readable recording media. By reading the program recorded on such a recording medium and executing it in the information processing apparatus, the function of the present embodiment may be realized by software.

FIG. 10A is a diagram illustrating a computer configuration applicable to the control method according to the embodiment of the present invention. The direction of the arrow in the drawing shows an example, and does not limit the direction of the signal between the blocks.

As shown in FIG. 10A, the information processing apparatus includes a memory 156 composed of a CPU (Central Processing Unit) 155, a RAM (Random Access Memory), and the like. The controller 2 of the above-described embodiment can be realized by the information processing device having such a hardware configuration. That is, a part or all of the controller 2 of FIG. 2 can also be realized by reading a program for executing each process as shown in FIG. 10B and causing the information processing apparatus to execute the program. Specifically, as shown in FIG. 10B, there are a pass access count confirmation process and a master controller number confirmation process. Further, the master switching process and the like as shown in FIG. 10B.

The program may also be distributed in the form of a recording medium on which the program is recorded. This program is a general-purpose semiconductor recording device such as CF (Compact Flash (registered trademark)) and SD (Secure Digital), a magnetic recording medium such as a flexible disk, or a CD-ROM (Compact Disc Read Only Memory). ) And other forms such as optical recording media.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto. It goes without saying that various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

Some or all of the above embodiments may also be described, but not limited to:
(Appendix 1) An extension management table that manages a host identifier and a master controller for each extent, and a master switching control means that switches the master controller for each extent according to access from a virtual machine. Storage device controller, including.
(Supplementary note 2) The control device for a storage device according to Supplementary note 1, wherein the extent management table manages the host identifier, the controller number of the master controller, and the number of path accesses for each extent.
(Appendix 3) The controller to which the path to which the path access count exceeds the first threshold value and the path access count exceeding the first threshold value is connected is different from the controller serving as the master. The control device for the storage device according to Appendix 2, which switches the controller to be the master while the device is running.
(Appendix 4) The controller to which the path to which the pass access count exceeds the first threshold value and the pass access count exceeding the first threshold value is connected and the controller to be the master The control device for a storage device according to Appendix 3, which is different and switches the controller to be the master when the number of pass accesses does not exceed the second threshold value.
(Appendix 5) Including a plurality of controllers to be the master.
The control device for a storage device according to any one of Supplementary note 1 to Supplementary note 4, wherein the master controller is connected to a plurality of host devices for which a virtual machine environment is constructed.
(Appendix 6) A storage device including a control device for the storage device according to any one of Supplementary note 1 to Supplementary note 5.
(Appendix 7) Holds the host identifier and the association of the master controller for each extent.
A method for controlling a storage device, which switches a controller to be a master for each extent based on the association according to an access from a virtual machine.
(Supplementary Note 8) The storage device control method according to Supplementary note 7, wherein the host identifier, the controller number of the master controller, and the path access count are associated with each extent.
(Appendix 9) The controller to which the path to which the path access count exceeds the first threshold value and the path access count exceeding the first threshold value is connected is different from the controller serving as the master. The method for controlling a storage device according to Appendix 8, wherein the controller to be the master is switched at the same time.
(Appendix 10) The controller to which the path corresponding to the path access count exceeds the first threshold value and the path access count exceeds the first threshold value is connected, and the controller serving as the master. The control method for a storage device according to Appendix 9, wherein the master controller is switched when the number of pass accesses does not exceed the second threshold value.
(Appendix 11) To the computer
Reference processing that refers to the extent management table that manages the host identifier and master controller for each extent,
A control program for a storage device that executes a master switching process for switching the master controller for each extent in response to access from a virtual machine.
(Supplementary note 12) The control program for a storage device according to Supplementary note 11, wherein the extent management table manages the host identifier, the controller number of the controller to be the master, and the number of path accesses for each extent.
(Appendix 13) The reference process is
The path access count confirmation process for confirming whether the pass access count exceeds the first threshold value and
The storage device according to Appendix 12, which includes a master controller confirmation process for confirming whether or not the controller to which the path corresponding to the path access count exceeding the first threshold value is connected is different from the master controller. Control program.
(Supplementary Note 14) The storage device according to Appendix 13, wherein the path access count confirmation process includes a process of confirming whether the pass access count exceeds the first threshold value and confirming whether or not the pass access count exceeds the second threshold value. Control program.

1 Disk array device 2 Controller 3 Disk unit 5 Host control unit 6 Disk control unit 10 HDD
20 Virtual machine environment 21 Host device 22 Virtual machine (VM)
25 Optimal path information acquisition notification 30 Extent management table 40 Master switching control means 31 table 50 Optimal path information return means 51 Optimal path change notification means 80 Disk array 150 Controller 151 Master switching control unit 152 Extent management table 155 CPU
156 Memory 160 Disk array 170 Disk array device

Claims (8)

A control device connected to a host device including a plurality of virtual machines , included in a storage device having a storage device , and controlling access from the host device to the logical disk of the storage device .
The logical disk of the storage device is composed of a plurality of extents .
Before each Symbol extent, the plurality of host identifier is information for discriminating the host device included virtual machine, the master controller number is the number of the master controller is a control device as a master among the plurality of the control device An extension management table that correlates and holds the number of path accesses, which is the number of accesses for each path that the host device has accessed the logical disk via the path connected between the control device and the host device.
The reference to the path access times, the master controller including control devices and the master switching control means for switching, of each said extent depending on the path access times. The number of pass accesses exceeds the first threshold value,
And when said path access number and the first threshold value beyond have controller connected to path was the mass octopus controller and are different, to switch the mass octopus controller, according to claim 1 of the control apparatus. Path access times of the mass octopus controller with different control unit connected to the path is above said first threshold value,
And when the path access times of the mass octopus controller connected to the path does not exceed the second threshold value, for switching the mass octopus controller, control apparatus according to claim 2. Includes a plurality of said mass octopus controller,
The mass octopus controller are connected to the host device that the virtual machine environment is built, the control device according to any one of claims 1 to 3. In any one of claims 1 to 4 including a control device according, storage device. A control method that is connected to a host device including a plurality of virtual machines, is included in a storage device having a storage device , and controls access from the host device to the logical disk of the storage device .
The logical disk of the storage device is composed of a plurality of extents .
The extent management table, for each of the extent, the plurality of host identifier is information for discriminating the host device included virtual machine, the number of the master controller is a control device as a master among the plurality of control devices A master controller number and a path access count, which is the number of accesses for each path by which the host device accesses the logical disk via a path connected between the control device and the host device , are associated and held.
The reference path access times, to switch the mass octopus controller for each of the extents in response to the pass number of accesses, the control method. The number of pass accesses exceeds the first threshold value,
And said path access times said first control threshold is connected to a path that exceeds device, when the mass octopus controller and are different, to switch the mass octopus controller, according to claim 6 control method. A control program connected to a host device including a plurality of virtual machines , included in a storage device having a storage device , and controlling access from the host device to the logical disk of the storage device .
The logical disk of the storage device is composed of a plurality of extents .
On your computer,
For each of the extensions, a host identifier that is information for identifying the host device that includes the virtual machine , a master controller number that is a master controller number that is a master control device among a plurality of control devices , and the control. The process of referring to the extension management table that holds the path access count , which is the number of accesses for each path that the host device accessed the logical disk via the path connected between the device and the host device.
The reference path access times, to execute a master switching processing for switching between the mass octopus controller for each of the extents in response to the pass number of accesses, the control program.

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