Host device with efficient automated seamless migration of logical storage devices across multiple access protocols

1. An apparatus comprising:

a host device comprising a processor coupled to a memory;

the host device being configured to communicate over a network with a storage system;

the host device being further configured:

to establish a migration session in the host device for migration of a source logical storage device accessible utilizing a first access protocol to a target logical storage device accessible utilizing a second access protocol different than the first access protocol; and

to migrate the source logical storage device to the target logical storage device utilizing a multi-path layer of the host device;

wherein the multi-path layer maintains separate device identities for the respective source and target logical storage devices in conjunction with the migration session but presents a corresponding composite device having a single device identity to one or more applications executing on the host device;

wherein the multi-path layer translates one or more commands directed to the composite device in the first access protocol to one or more commands in the second access protocol by modifying at least a subset of the commands in the first access protocol to produce corresponding commands in the second access protocol; and

wherein the host device in conjunction with migrating the source logical storage device to the target logical storage device is further configured:

to direct the storage system to establish a copy relationship between the source logical storage device and the target logical storage device;

to obtain an indication from the storage system that the copy relationship has been established;

responsive to the obtained indication, to activate the previously-established migration session with background copying disabled;

to start sending input-output operations to the target logical storage device instead of to the source logical storage device; and

to enable background copying for the activated migration session such that data of the source logical storage device is copied to the target logical storage device by the storage system.

2. The apparatus of claim 1 wherein the first access protocol comprises a Small Computer System Interface (SCSI) access protocol and the second access protocol comprises a Non-Volatile Memory Express (NVMe) access protocol.

3. The apparatus of claim 2 wherein the SCSI access protocol comprises a SCSI over Fibre Channel (SCSI-FC) access protocol and the NVMe access protocol comprises an NVMe over Fibre Channel (NVMeoFC) access protocol.

4. The apparatus of claim 1 wherein the source logical storage device and the target logical storage device are both located on the same storage system.

5. The apparatus of claim 1 wherein the storage system comprises a first storage system that includes the source logical storage device and further wherein the target logical storage device is located on a second storage system, the host device being configured to communicate over the network with the first and second storage systems.

6. The apparatus of claim 1 wherein the multi-path layer comprises at least one multi-path input-output driver configured to control delivery of input-output operations from the host device to the storage system over selected paths through the network, the multi-path input-output driver being further configured to maintain the separate device identities for the respective source and target logical storage device, to present the corresponding composite device having the single device identity, and to translate the one or more commands directed to the composite device.

7. The apparatus of claim 1 wherein directing the storage system to establish a copy relationship between the source logical storage device and the target logical storage device comprises directing the storage system to establish a copy relationship between the source logical storage device and the target logical storage device that when activated causes copying of data from the source logical storage device to the target logical storage device.

8. The apparatus of claim 7 wherein the copy relationship is established but is not activated to perform the copying of data from the source logical storage device to the target logical storage device.

9. The apparatus of claim 1 wherein obtaining an indication from the storage system that the copy relationship has been established comprises:

sending a command to the storage system; and

obtaining the indication responsive to the command.

10. The apparatus of claim 1 wherein establishing the migration session in the host device for migration of the source logical storage device to the target logical storage device comprises configuring but not activating the migration session in the host device.

11. The apparatus of claim 1 wherein activating the previously-established migration session with background copying disabled is configured to ensure that any input-output operation sent to the target logical storage device instead of to the source logical storage device will cause corresponding data to be copied from the source logical storage device to the target logical storage device.

12. The apparatus of claim 1 wherein the host device is further configured to terminate the activated migration session responsive to completion of the copying of the data of the source logical storage device to the target logical storage device by the storage system, and wherein the source logical storage device is deprecated or repurposed responsive to termination of the activated migration session.

13. The apparatus of claim 1 further comprising one or more additional host devices each configured to communicate over the network with the storage system, and wherein each of the host devices separately moves from utilization of the source logical storage device to utilization of the target logical storage device.

14. A method performed by a host device configured to communicate over a network with a storage system, comprising:

establishing a migration session in the host device for migration of a source logical storage device accessible utilizing a first access protocol to a target logical storage device accessible utilizing a second access protocol different than the first access protocol; and

migrating the source logical storage device to the target logical storage device utilizing a multi-path layer of the host device;

wherein the multi-path layer maintains separate device identities for the respective source and target logical storage devices in conjunction with the migration session but presents a corresponding composite device having a single device identity to one or more applications executing on the host device;

wherein the multi-path layer translates one or more commands directed to the composite device in the first access protocol to one or more commands in the second access protocol by modifying at least a subset of the commands in the first access protocol to produce corresponding commands in the second access protocol;

the method further comprising:

directing the storage system to establish a copy relationship between the source logical storage device and the target logical storage device;

obtaining an indication from the storage system that the copy relationship has been established;

responsive to the obtained indication, activating the previously-established migration session with background copying disabled;

starting to send input-output operations to the target logical storage device instead of to the source logical storage device; and

enabling background copying for the activated migration session such that data of the source logical storage device is copied to the target logical storage device by the storage system; and

wherein the host device comprises a processor coupled to a memory.

15. The method of claim 14 wherein activating the previously-established migration session with background copying disabled is configured to ensure that any input-output operation sent to the target logical storage device instead of to the source logical storage device will cause corresponding data to be copied from the source logical storage device to the target logical storage device.

16. The method of claim 14 wherein the multi-path layer comprises at least one multi-path input-output driver configured to control delivery of input-output operations from the host device to the storage system over selected paths through the network, the multi-path input-output driver being further configured to maintain the separate device identities for the respective source and target logical storage device, to present the corresponding composite device having the single device identity, and to translate the one or more commands directed to the composite device.

17. A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code, when executed by a host device comprising a processor coupled to a memory and configured to communicate over a network with a storage system, causes the host device:

to establish a migration session in the host device for migration of a source logical storage device accessible utilizing a first access protocol to a target logical storage device accessible utilizing a second access protocol different than the first access protocol; and

to migrate the source logical storage device to the target logical storage device utilizing a multi-path layer of the host device;

wherein the multi-path layer maintains separate device identities for the respective source and target logical storage devices in conjunction with the migration session but presents a corresponding composite device having a single device identity to one or more applications executing on the host device;

wherein the multi-path layer translates one or more commands directed to the composite device in the first access protocol to one or more commands in the second access protocol by modifying at least a subset of the commands in the first access protocol to produce corresponding commands in the second access protocol; and

wherein the program code when executed by the host device further causes the host device:

to direct the storage system to establish a copy relationship between the source logical storage device and the target logical storage device;

to obtain an indication from the storage system that the copy relationship has been established;

responsive to the obtained indication, to activate the previously-established migration session with background copying disabled;

to start sending input-output operations to the target logical storage device instead of to the source logical storage device; and

to enable background copying for the activated migration session such that data of the source logical storage device is copied to the target logical storage device by the storage system.

18. The computer program product of claim 17 wherein activating the previously-established migration session with background copying disabled is configured to ensure that any input-output operation sent to the target logical storage device instead of to the source logical storage device will cause corresponding data to be copied from the source logical storage device to the target logical storage device.

19. The computer program product of claim 17 wherein establishing the migration session in the host device for migration of the source logical storage device to the target logical storage device comprises configuring but not activating the migration session in the host device.

20. The computer program product of claim 17 wherein the multi-path layer comprises at least one multi-path input-output driver configured to control delivery of input-output operations from the host device to the storage system over selected paths through the network, the multi-path input-output driver being further configured to maintain the separate device identities for the respective source and target logical storage device, to present the corresponding composite device having the single device identity, and to translate the one or more commands directed to the composite device.