Data migration using coherency groups

Abstract

The invention relates to data migration using coherency groups. Example implementations relate to computer data storage. In some examples, a controller establishes a migration link between a first storage device and a second storage device, and creates a coherency group including a copy volume and a control volume stored on the first storage device. The controller initiates a copy of data from the copy volume to the proxy volume on the second storage device based on the coherency group. In response to completion of the data copy from the copy volume to the proxy volume, the controller initiates a copy of the proxy volume to the second copy device. Further, in response to completion of the replication of the proxy volume, the controller transfers a copy of the control volume to the second storage device, where the transfer of the copy of the control volume causes the migration of the coherence group to be completed.

Description

Background Art

[0001] Computing devices may include components such as processors, memory, cache systems, and storage devices. Storage devices may include hard disk drives that use magnetic media to store and retrieve blocks of data. Some storage systems can transfer data between different locations or devices. For example, some systems can transfer and store copies of important data for archiving and recovery purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Some embodiments are described with respect to the following figures.

[0003] Figure 1 is a schematic diagram of an example system according to some embodiments.

[0004] Figure 2 is an illustration of an example process according to some implementations.

[0005] Figures 3A to 3F is an illustration of example operations according to some implementations.

[0006] Figure 4 is a schematic diagram of an example management system according to some embodiments.

[0007] Figure 5 is an illustration of an example process according to some implementations.

[0008] Figure 6 is a diagram of an example machine-readable medium having instructions stored thereon, according to some implementations.

[0009] Throughout the drawings, like reference numerals designate similar, but not necessarily identical, elements. The drawings are not necessarily drawn to scale, and the size of some parts may be exaggerated to more clearly illustrate the examples shown. Furthermore, the drawings provide examples and / or implementations consistent with the description; however, the description is not limited to the examples and / or implementations provided in the drawings. DETAILED DESCRIPTION

[0010] In the present disclosure, unless the context clearly indicates otherwise, the use of the terms "a," "an," or "the" is intended to include the plural forms as well. Similarly, when used in the present disclosure, the terms "includes / including / comprises / comprising" or "have / having" specify the presence of stated elements, but do not preclude the presence or addition of other elements.

[0011] As used herein, a "storage system" may include a storage device or a storage device array. The storage system may also include (multiple) storage controllers that manage access to (multiple) storage devices. A "data unit" may refer to any data portion that can be individually identified in a storage system. In some cases, a data unit may refer to a block, a collection of blocks, or any other data portion. In some examples, the storage system may store the data units in a persistent storage device. The persistent storage device may be implemented using one or more (multiple) persistent (e.g., non-volatile) storage devices (such as (multiple) disk-based storage devices (e.g., (multiple) hard disk drives (HDDs)), (multiple) solid-state devices (SSDs) (such as (multiple) flash memory devices), etc.), or a combination thereof. As used herein, a "controller" may refer to a hardware processing circuit, which may include any one or some combination of a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, a digital signal processor, or other hardware processing circuits. Alternatively, a "controller" may refer to a combination of a hardware processing circuit and machine-readable instructions (software and / or firmware) that can be executed on the hardware processing circuit.

[0012] In some examples, a collection of input data (e.g., a real-time data value stream) can be persistently stored on a storage system. The storage system can include two (or more) storage devices that store replicated copies of the data. For example, the storage system can include a first storage array that stores a copy of the data collection, and can also include a second storage array that stores a replicated copy of the data collection stored on the first storage array. In this way, valuable or business-critical data (e.g., bank transaction data) can be protected from loss in the event of a failure of a single device or array.

[0013] In some examples, an existing storage system may be replaced with a different storage system (e.g., a newer storage system with improved storage capacity, data throughput, data security, etc.). The replacement process may include migrating data stored on the existing storage system to the different storage system. However, the two storage systems may not be able to perform the data migration without interrupting normal storage functionality. For example, the two storage systems may be provided by different vendors (or may use different product lines or device generations from the same vendor) and may not have compatible functionality for performing the data migration while also receiving new input data and maintaining a full copy of the stored data. Therefore, in such examples, performing the data migration may involve interrupting the receipt of new input data and / or not maintaining a full copy of the stored data during the entire period of the data migration. Therefore, in such examples, performing the data migration may negatively impact the reliability and performance of one or both of the storage systems.

[0014] According to some embodiments of the present disclosure, a controller may perform a migration process to replace an existing ("source") storage system with a different ("destination") storage system. The source storage system and the destination storage system may each include a primary storage device and a secondary copy device. In some embodiments, the migration process may include defining a consistency group that includes all replicated volumes on the source storage device (i.e., volumes copied to the source copy device) and also includes a virtual control volume that has no data content. The migration process may also include transferring the replicated volumes from the source storage device to the destination storage device and initiating data replication from the destination storage device to the destination copy device. Further, after completing the data replication, the migration process may include transferring the control volume from the source storage device to the destination storage device, thereby completing the migration of the consistency group. In this way, the migration process may be completed while maintaining data storage and replication. Reference is made below to Figures 1 to 6 Further discussion of various aspects of the disclosed migration process.

[0015] Figure 1 -Example System

[0016] Figure 1 An example system 100 is shown in accordance with some embodiments. The system 100 may include a client device 105, a source system 112, and a destination system 122. The source system 112 may include a source storage device 110 and a source replication device 115. In some embodiments, the source storage device 110 may receive data from the client device 105 and may persistently store the received data. Further, some or all of the data stored on the source storage device 110 may be copied or "replicated" to be persistently stored on the source replication device 115. For example, the source storage device 110 may store data in a set of volumes (e.g., logical storage units) that are automatically replicated to the source replication device 115 (also referred to herein as "replicated volumes"). In this manner, data received from the client device 105 may be persistently stored in two different storage devices 110, 115 and, therefore, may be protected from loss due to a failure of one of the two storage devices 110, 115.

[0017] In some embodiments, source system 112 may be replaced by destination system 122, which includes destination storage device 120 and destination replication device 125. For example, the owner or administrator of system 100 may determine that source system 112 is an older storage system that does not meet a set of requirements (e.g., based on storage capacity, data throughput, data security, etc.), and may therefore replace source system 112 with a newer destination system 122 that can meet the set of requirements. In some examples, source system 112 and destination system 122 may be provided by different vendors, or may utilize different product lines or device generations from the same vendor.

[0018] In some embodiments, the process of replacing the source system 112 with the destination system 122 (also referred to herein as a "migration process") may include copying data stored on the source system 112 to the destination system 122. Further, after the migration process is completed, the destination storage device 120 may receive input data from the client device 105 and may persistently store the received data. Further, the data stored on the destination storage device 120 may be copied to the destination replication device 125.

[0019] In some embodiments, some or all of devices 110, 115, 120, 125 may be implemented using persistent (e.g., non-volatile) storage device(s), such as disk-based storage device(s) (e.g., hard disk drive(s) (HDD(s)), solid-state device(s) (e.g., flash memory device(s)), etc.). For example, devices 110, 115, 120, 125 may be different storage arrays each including multiple storage components (e.g., HDDs, SSDs, etc.).

[0020] In some embodiments, the destination storage device 120 may include a controller 130 for managing storage operations. The controller 130 may be implemented via hardware (e.g., electronic circuitry) or a combination of hardware and programming (e.g., including at least one processor and instructions executable by the at least one processor and stored on at least one machine-readable storage medium).

[0021] In some embodiments, the controller 130 may include functionality for managing a migration process to replace the source system 112 with the destination system 122. The controller 130 may initiate the migration process in response to receiving a command or message (e.g., a request from a human user to perform a migration process). In some embodiments, the migration process may include defining a consistency group that includes all replicated volumes on the source storage device 110 (i.e., volumes that are replicated to the source replication device 115) and also includes a virtual control volume that has no data content. The migration process may also include transferring the replicated volumes from the source storage device 110 to the destination storage device 120 and then initiating data replication from the destination storage device 120 to the destination replication device 125. Further, after completing the data replication, the migration process may include transferring the control volume from the source storage device 110 to the destination storage device 120, thereby completing the migration of the consistency group. In this way, the migration process may be completed while maintaining data storage and replication. Reference is made below to Figures 2 to 3F Describes the example migration process in more detail.

[0022] Figures 2 to 3F - Example migration process

[0023] Figure 2 An example migration process 200 is shown in accordance with some embodiments. The process 200 may be implemented in hardware or a combination of hardware and programming (e.g., machine-readable instructions executable by (multiple) processors). The machine-readable instructions may be stored in a non-transitory computer-readable medium such as an optical storage device, a semiconductor storage device, or a magnetic storage device. The machine-readable instructions may be executed by a single processor, multiple processors, a single processing engine, multiple processing engines, etc. For illustration purposes, reference may be made to a diagram illustrating an example embodiment. Figure 1 and Figures 3A to 3F hereinafter are described the details of process 200. However, other implementations are possible.

[0024] Block 210 may include receiving a request to initiate a migration from a source storage system to a destination storage system. Block 220 may include establishing a migration link between the source storage device and the destination storage device. Block 230 may include establishing a replication link between the destination storage device and the destination replication device. For example, referring to Figure 3A, the source storage device 110 receives data input / output (I / O) from the client device 105 via a data link 316. Furthermore, the source storage device 110 stores the data in a replicated volume 310, which is automatically copied to the source replication device 115. Subsequently, the controller 130 receives a request (e.g., a user command, a program instruction, etc.) to initiate a migration from the source system 112 to the destination system 122. In response to the request, the controller 130 establishes a migration link 312 between the source storage device 110 and the destination storage device 120. Furthermore, the controller 130 establishes a replication link 314 between the destination storage device 120 and the destination replication device 125.

[0025] Reference again Figure 2 , block 240 may include creating a set of proxy volumes on the destination storage device that are associated with a set of replicated volumes on the source storage device. Figure 3B , the controller initiates or registers the proxy volumes 330 on the destination storage device 120 (also referred to as "admitting" the proxy volumes 330 on the destination storage device 120). Each proxy volume 330 represents (or is otherwise associated with) a different replicated volume 310 on the source storage device 110. When each proxy volume 330 is registered or admitted on the destination storage device 120, the proxy volume 330 is viewed by the client device 105 as representing the corresponding replicated volume 310.

[0026] Reference again Figure 2 , block 250 may include establishing a data link between the client device and the destination storage device. Figure 3B , the controller establishes a data link 322 between the client device 105 and the destination storage device 120. Further, the client device 105 sends data I / O to the proxy volume 330 via the data link 322, and the proxy volume 330 forwards the data I / O (represented by dashed arrow 326) to the corresponding replicated volume 310 (e.g., via the migration link 312).

[0027] Reference again Figure 2 , block 260 may include creating a control volume on the source storage device. For example, referring to Figure 3B , the controller creates a control volume 320 on the source storage device 110 . In some embodiments, the control volume 320 is a virtual volume that does not include any data and is used to control the progress of the migration from the source system 112 to the destination system 122 .

[0028] Reference again Figure 2 , block 270 may include creating a consistency group including the replicated volume and the control volume of the source storage device. Figure 3C, the controller creates a consistency group 340 that includes the replicated volume 310 and the control volume 320 (on the source storage device 110). As used herein, the term "consistency group" refers to a group of specified data elements (e.g., volumes, files, etc.) that are migrated together (e.g., during a single migration operation). In some embodiments, creating the consistency group 340 initiates or defines a group migration that will not be completed until all data elements in the consistency group 340 (i.e., both the replicated volume 310 and the control volume 320) are fully migrated to the destination storage device 120. Further, the controller removes the data link 316 between the client device 105 and the source storage device 110.

[0029] Reference again Figure 2 , block 280 may include initiating a data copy from the replicated volume of the source storage device to the proxy volume of the destination storage device based on the consistency group. Figure 3C , the controller initiates a data copy 342 from the replicated volume 310 to the proxy volume 330 (e.g., via the migration link 312). The data copy 342 can be performed based on (or in accordance with) the consistency group 340. For example, in some embodiments, the data copy 342 transfers a copy of the first portion of the consistency group 340 (i.e., the replicated volume 310) to the destination storage device 120, but does not transfer a copy of the second portion of the consistency group 340 (i.e., the control volume 320) to the destination storage device 120. As such, the consistency group 340 is not fully migrated upon completing the data copy 342 (i.e., by copying only the data of the replicated volume 310 to the destination storage device 120).

[0030] In some embodiments, the storage systems 112 and 122 can continue to perform migration operations while the data copy 342 is being performed. For example, the proxy volume 330 can continue to forward data I / O to the replicated volume 310 on the source storage device 110, and the replicated volume 310 on the source storage device 110 can continue to be replicated to the replica storage device 115.

[0031] Reference again Figure 2 , block 290 may include: upon completion of the data copy, initiating replication of the proxy volume from the destination storage device to the destination replication device. Figure 3D The controller determines that data copy 342 is complete and, in response, initiates data copy 344 of proxy volume 330 from destination storage device 120 to destination copy device 125 (eg, via copy link 314 ). Data copy 344 may generate replicated volume 310 on destination copy device 125 .

[0032] In some embodiments, the storage systems 112 and 122 can continue to perform migration operations while data replication 344 is being performed. For example, the proxy volume 330 can continue to forward data I / O to the replicated volume 310 on the source storage device 110, and the replicated volume 310 on the source storage device 110 can continue to be replicated to the replication storage device 115.

[0033] Reference again Figure 2 , block 295 may include: upon completion of the replication of the proxy volume, copying the control volume from the source storage device to the destination storage device. After block 295, process 200 may be complete. For example, referring to Figure 3E , the controller 130 determines that the data copy 344 has completed, and in response, performs a data copy 352 (eg, via the migration link 314 ) to copy the control volume 320 from the source storage device 110 to the destination storage device 120 .

[0034] In some embodiments, copying the control volume 320 to the destination storage device 120 completes the migration of the consistency group 340 (including the replicated volume 310 and the control volume 320). Further, upon completing the migration of the consistency group 340, one or more actions may be performed to complete the switch from the source system 112 to the destination system 122. For example, referring to Figure 3F , the controller 130 deletes the consistency group 340, deletes the copies of the control volume 320 (in the source storage device 110 and the destination storage device 120), and also removes the migration link 312. Further, the controller 130 converts the proxy volumes 330 into replicated volumes 310 on the destination storage device 120. After converting the proxy volumes 330 into replicated volumes 310 on the destination storage device 120, these replicated volumes 310 no longer forward data I / O to the replicated volumes 310 on the source storage device 110. More specifically, data I / O is applied only to the replicated volumes 310 on the destination storage device 120 and is replicated on the destination replication device 125. Subsequently, the storage system 112 is no longer updated with new data and, therefore, may store stale data 360 (e.g., an older copy of the replicated volume 310) or may be taken offline.

[0035] Figure 4 -Sample Management System

[0036] Figure 4 A schematic diagram of an example management system 400 is shown. In some examples, the management system 400 may generally correspond to the controller 130 (e.g., Figure 1As shown, management system 400 may include a controller 402 and a machine-readable storage device 405 including instructions 410-450. Machine-readable storage device 405 may be a non-transitory medium. Instructions 410-450 may be executed by controller 402 or by a processing engine included in controller 402.

[0037] Instruction 410 may be executed to establish a migration link between a first storage device and a second storage device, wherein the first storage device stores a set of replicated volumes replicated on the first replication device. Figure 3A , the source storage device 110 receives data input / output (I / O) from the client device 105 and stores the data in a replicated volume 310 that is automatically copied to the source replication device 115. The controller 130 receives the request to initiate the migration and, in response, establishes a migration link 312 between the source storage device 110 and the destination storage device 120. In some embodiments, the controller 130 establishes a replication link 314 between the destination storage device 120 and the destination replication device 125 and grants a proxy volume 330 on the destination storage device 120. Further, referring to Figure 3B , the controller 130 grants a proxy volume 330 on the destination storage device 120 , establishes a data link 322 between the client device 105 and the destination storage device 120 , and creates a control volume 320 on the source storage device 110 .

[0038] Instructions 420 may be executed to create a consistency group including the set of replicated volumes and the control volume stored on the first storage device, wherein the consistency group is a group of data elements that are migrated together. Figure 3C The controller creates a consistency group 340 including the replicated volume 310 and the control volume 320 stored on the source storage device 110 . Further, the controller removes the data link 316 between the client device 105 and the source storage device 110 .

[0039] Instruction 430 may be executed to initiate a data copy from the set of replicated volumes to a set of proxy volumes on a second storage device based on the consistency group, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes. Figure 3B , the client device 105 sends data I / O to the proxy volume 330 via the data link 322. The proxy volume 330 forwards the received data I / O (indicated by the dashed arrow 326) to the corresponding replicated volume 310 (e.g., via the migration link 312). Figure 3C , the controller initiates a data copy 342 from the replicated volume 310 to the proxy volume 330 (eg, via the migration link 312 ). The data copy 342 is performed based on the consistency group 340 .

[0040] Instructions 440 may be executed to initiate replication of the set of proxy volumes from the second storage device to the second replication device in response to completion of the data copy from the set of replication volumes to the set of proxy volumes. Figure 3D The controller determines that data copy 342 is complete and, in response, initiates data copy 344 of proxy volume 330 from destination storage device 120 to destination copy device 125 (eg, via copy link 314). Data copy 344 stores replicated volume 310 on destination copy device 125.

[0041] Instruction 450 may be executed to, in response to completion of the replication of the group of proxy volumes from the second storage device to the second replication device, transfer the copy of the control volume from the first storage device to the second storage device, wherein the transfer of the copy of the control volume to the second storage device completes the migration of the consistency group from the first storage device to the second storage device. Figure 3E , the controller determines that the data copy 344 has completed and, in response, performs a data copy 352 (e.g., via the migration link 314) to copy the control volume 320 from the source storage device 110 to the destination storage device 120. In some embodiments, copying the control volume 320 to the destination storage device 120 completes the migration of the consistency group 340 (including the replicated volume 310 and the control volume 320).

[0042] In some embodiments, after (or as part of) the completion of the migration of the consistency group 340, one or more actions may be performed to complete the switch from the source system 112 to the destination system 122. For example, referring to Figure 3F , the controller deletes the consistency group 340 , deletes the copies of the control volume 320 (in the source storage device 110 and the destination storage device 120 ), and also removes the migration link 312 . Further, the controller 130 converts the proxy volume 330 into a replicated volume 310 on the destination storage device 120 .

[0043] Figure 5 - Example process

[0044] Figure 5 An example process 500 is shown according to some embodiments. In some examples, the process 500 can be performed by a processor or controller (e.g., Figure 1130). Process 500 may be implemented in hardware or a combination of hardware and programming (e.g., machine-readable instructions executable by (or multiple) processors). The machine-readable instructions may be stored in a non-transitory computer-readable medium such as an optical storage device, a semiconductor storage device, or a magnetic storage device. The machine-readable instructions may be executed by a single processor, multiple processors, a single processing engine, multiple processing engines, etc. However, other implementations are possible.

[0045] Block 510 may include establishing, by a controller, a migration link between a first storage device and a second storage device, wherein the first storage device stores a set of replicated volumes replicated on the first replication device. Block 520 may include creating, by the controller, a consistency group including the set of replicated volumes stored on the first storage device and a control volume, wherein the consistency group is a set of data elements that are migrated together.

[0046] Block 530 may include the controller initiating, based on the consistency group, a data copy from the set of replicated volumes to a set of proxy volumes on the second storage device, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes. Block 540 may include: in response to completion of the data copy from the set of replicated volumes to the set of proxy volumes, the controller initiating a replication of the set of proxy volumes from the second storage device to the second replicated device.

[0047] Block 550 may include: in response to completion of the replication of the group of proxy volumes from the second storage device to the second replication device, transferring, by the controller, the replica of the control volume from the first storage device to the second storage device, wherein the migration of the replica of the control volume to the second storage device completes the migration of the consistency group from the first storage device to the second storage device. Blocks 510-550 may generally correspond to instructions 410-450 (e.g., as described above) with reference to FIG. Figure 4 ) described in the example shown.

[0048] Figure 6 - Example machine-readable medium

[0049] Figure 6 A machine-readable medium 600 is shown having stored thereon instructions 610-650 according to some embodiments. The instructions 610-650 may be executed by a controller (e.g., Figure 1 The machine-readable medium 600 may be a non-transitory storage medium, such as an optical storage medium, a semiconductor storage medium, or a magnetic storage medium. The instructions 610-650 may generally correspond to the instructions 410-450 (e.g., the instructions 410-450 described above). Figure 4 ) described in the example shown.

[0050] Instructions 610 may be executed to establish a migration link between a first storage device and a second storage device, wherein the first storage device stores a set of replicated volumes replicated on the first replicated device. Instructions 620 may be executed to create a consistency group including the set of replicated volumes and a control volume stored on the first storage device, wherein the consistency group is a group of data elements that are migrated together. Instructions 630 may be executed to initiate a data copy from the set of replicated volumes to a set of proxy volumes on the second storage device based on the consistency group, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes.

[0051] Instruction 640 may be executed to, in response to completion of copying data from the group of replicated volumes to the group of proxy volumes, initiate replication of the group of proxy volumes from the second storage device to the second replication device. Instruction 650 may be executed to, in response to completion of replication of the group of proxy volumes from the second storage device to the second replication device, migrate the replica of the control volume from the first storage device to the second storage device, wherein migrating the replica of the control volume to the second storage device completes migration of the consistency group from the first storage device to the second storage device.

[0052] in conclusion

[0053] According to some embodiments described herein, a controller may perform a migration process to replace a source storage system with a destination storage system. The source storage system and the destination storage system may each include a primary storage device and a secondary replication device. In some embodiments, the migration process may include defining a consistency group that includes all replicated volumes on the source storage device and also includes a virtual control volume that has no data content. The migration process may also include transferring the replicated volumes from the source storage device to the destination storage device and initiating data replication from the destination storage device to the destination replication device. Further, after completing the data replication, the migration process may include transferring the control volume from the source storage device to the destination storage device, thereby completing the migration of the consistency group. In this way, the migration process may be completed while maintaining data storage and replication.

[0054] Note that although Figures 1 to 6 Various examples are shown, but the embodiments are not limited in this respect. For example, referring to Figure 1 , it is contemplated that system 100 may include additional devices and / or components, fewer components, different components, a different arrangement, etc. In another example, it is contemplated that each of devices 110, 115, 125 may further include a controller for managing the operation of the respective device 110, 115, 125. In yet another example, it is contemplated that the functionality of the system 100 described above may be included in any other engine or software. Other combinations and / or variations are also possible.

[0055] Data and instructions are stored in corresponding storage devices implemented as one or more computer-readable or machine-readable storage media. Storage media include various forms of non-transitory memory, including: semiconductor memory devices such as dynamic random access memory or static random access memory (DRAM or SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory; magnetic disks such as fixed floppy disks and removable disks; other magnetic media, including magnetic tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices.

[0056] Note that the instructions discussed above may be provided on one computer-readable or machine-readable storage medium, or alternatively, may be provided on multiple computer-readable or machine-readable storage media distributed in a large system having potentially multiple nodes. Such one or more computer-readable or machine-readable storage media are considered part of an article (or product). An article or product may refer to any manufactured single component or multiple components. The one or more storage media may be located in the machine that runs the machine-readable instructions, or at a remote site from which the machine-readable instructions may be downloaded over a network for execution.

[0057] In the foregoing description, numerous details have been set forth to facilitate an understanding of the subject matter disclosed herein. However, embodiments may be practiced without some of these details. Other embodiments may include modifications and variations of the details discussed above. The appended claims are intended to cover such modifications and variations.

[0058] In the present disclosure, unless the context clearly indicates otherwise, the use of the terms "a," "an," or "the" is intended to include the plural forms as well. Similarly, when used in the present disclosure, the terms "includes / including / comprises / comprising" or "have / having" specify the presence of stated elements, but do not preclude the presence or addition of other elements.

Claims

1. A management system, comprising: Controller; as well as a machine-readable storage device storing instructions executable by the processor to: Establishing a migration link between a first storage device and a second storage device, wherein the first storage device stores a set of replicated volumes replicated on the first replication device; creating a consistency group including the set of replica volumes and the control volume stored on the first storage device, wherein the consistency group is a group of data elements that are migrated together; Initiating a data copy from the set of replicated volumes to a set of proxy volumes on the second storage device based on the consistency group, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes; In response to completion of the data copying from the set of replication volumes to the set of proxy volumes, initiating replication of the set of proxy volumes from the second storage device to the second replication device; and In response to the completion of the replication of the group of proxy volumes from the second storage device to the second replication device, the copy of the control volume is transferred from the first storage device to the second storage device, wherein the transfer of the copy of the control volume to the second storage device completes the migration of the consistency group from the first storage device to the second storage device.

2. The management system of claim 1 , comprising instructions executable by the controller to: The control volume is created as an empty volume included in the first storage device.

3. The management system of claim 1 , comprising instructions executable by the controller to: After completing the migration of the consistency group, the group of proxy volumes is converted into a second group of replicated volumes replicated on the second replication device.

4. The management system of claim 1 , comprising instructions executable by the controller to: After completing the migration of the consistency group: Deleting the consistency group; deleting the control volume stored on the first storage device; and The control volume stored on the second storage device is deleted.

5. The management system of claim 1 , comprising instructions executable by the controller to: performing the data copy using the migration link between the first storage device and the second storage device; and After completing the migration of the consistency group, the migration link between the first storage device and the second storage device is removed.

6. The management system of claim 1 , comprising instructions executable by the controller to: Establishing a first data link between the client device and the second storage device; receiving the I / O transaction from the client device via the first data link; as well as The second data link between the client device and the first storage device is removed.

7. The management system according to claim 1, wherein: The control volume is not replicated on the first replication device.

8. The management system according to claim 1, wherein: The first storage device and the first replication device use a first storage technology, and wherein the second storage device and the second replication device use a second storage technology different from the first storage technology.

9. The management system according to claim 1, wherein: The controller is included in one of the second storage device and a system management device.

10. A method comprising: A controller establishes a migration link between a first storage device and a second storage device, wherein the first storage device stores a group of replicated volumes replicated on the first replication device; creating, by the controller, a consistency group comprising the set of replica volumes and a control volume stored on the first storage device, wherein the consistency group is a group of data elements that are migrated together; The controller initiates a data copy from the set of replicated volumes to a set of proxy volumes on the second storage device based on the consistency group, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes; In response to completion of the data copying from the group of replication volumes to the group of proxy volumes, initiating, by the controller, replication of the group of proxy volumes from the second storage device to the second replication device; and In response to the completion of the replication of the group of proxy volumes from the second storage device to the second replication device, the controller transfers the copy of the control volume from the first storage device to the second storage device, wherein the transfer of the copy of the control volume to the second storage device completes the migration of the consistency group from the first storage device to the second storage device.

11. The method of claim 10, comprising: Establishing a first data link between the client device and the second storage device; receiving the I / O transaction from the client device via the first data link; creating the control volume as an empty volume included in the first storage device; as well as The second data link between the client device and the first storage device is removed.

12. The method of claim 10, comprising, after completing the migration of the consistency group: removing the migration link between the first storage device and the second storage device; and The set of proxy volumes is converted into a second set of replicated volumes replicated on the second replication device.

13. The method of claim 12, comprising, after completing the migration of the consistency group: Deleting the consistency group; deleting the control volume stored on the first storage device; and The control volume stored on the second storage device is deleted.

14. The method of claim 10, wherein: The first storage device and the first replication device use a first storage technology, and wherein the second storage device and the second replication device use a second storage technology different from the first storage technology.

15. The method of claim 1, wherein: The controller is included in one of the second storage device and a system management device.

16. A non-transitory machine-readable medium storing instructions, the instructions, when executed, causing a controller to: A migration link is established between the first storage device and the second storage device, wherein: The first storage device stores a set of replicated volumes replicated on the first replication device; creating a consistency group including the set of replica volumes and the control volume stored on the first storage device, wherein the consistency group is a group of data elements that are migrated together; Initiating a data copy from the set of replicated volumes to a set of proxy volumes on the second storage device based on the consistency group, wherein the proxy volumes forward input / output (I / O) transactions to the set of replicated volumes; In response to completion of the data copying from the set of replication volumes to the set of proxy volumes, initiating replication of the set of proxy volumes from the second storage device to the second replication device; and In response to the completion of the replication of the group of proxy volumes from the second storage device to the second replication device, the copy of the control volume is transferred from the first storage device to the second storage device, wherein the transfer of the copy of the control volume to the second storage device completes the migration of the consistency group from the first storage device to the second storage device.

17. The non-transitory machine-readable medium of claim 16, comprising instructions that, when executed, cause the controller to: Establishing a first data link between the client device and the second storage device; receiving the I / O transaction from the client device via the first data link; creating the control volume as an empty volume included in the first storage device; as well as The second data link between the client device and the first storage device is removed.

18. The non-transitory machine-readable medium of claim 16, comprising instructions that, when executed, cause the controller to: After completing the migration of the consistency group: removing the migration link between the first storage device and the second storage device; and The set of proxy volumes is converted into a second set of replicated volumes replicated on the second replication device.

19. The non-transitory machine-readable medium of claim 16, comprising instructions that, when executed, cause the controller to: After completing the migration of the consistency group: Deleting the consistency group; deleting the control volume stored on the first storage device; and The control volume stored on the second storage device is deleted.

20. The non-transitory machine-readable medium of claim 16, wherein: The first storage device and the first replication device use a first storage technology, and wherein the second storage device and the second replication device use a second storage technology different from the first storage technology.

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