Workflow for performing Volume Migration

REST API Reference Guide for Virtual Storage Platform 5000, Virtual Storage Platform E Series, and Virtual Storage Platform G/F Series

Part Number
The following explains how to perform migrations by using Volume Migration, which is executed by the REST API.

Preparing for migration

Before starting migration, prepare a volume as the migration destination (target volume). You must set an LU path for the target volume.

The following figure shows the workflow.

Creating volumes (target volumes)
Create target volumes to which data is to be migrated.
Creating a host group
Create a host group so that LU paths can be set for the target volumes. The host group does not need to be allocated to the host. You can use an existing host group, but it must not include the volumes to be migrated (source volumes).
Setting LU paths
Specify the host group that you created for the target volumes, and then set LU paths.

Migrating data

Create Volume Migration pairs by specifying the source volumes as the P-VOLs and the target volumes as the S-VOLs, and then copy the data. You can perform operations on copy pairs in units of copy groups. A copy group is a group made up of copy pairs. Each copy group consists of a device group that is made up of P-VOLs and a device group made up of S-VOLs.

The following figure shows the workflow.

Creating pairs (Volume Migration)
Use the source volumes and the target volumes to create Volume Migration pairs. When a Volume Migration pair is created, the pair status is SMPL. Data is not copied until migration is performed.
Migrating data
Copy data from the source volumes to the target volumes in units of pairs or copy groups. When data copying is complete, the LDEV IDs and the path settings of the source volumes and the target volumes are switched, and the I/O from the host switches to the target volumes.
Deleting pairs (Volume Migration)
After the migration job is complete, if migration was successful, delete the pairs for migration.
Canceling migration
Cancel migration to stop the migration processing or if a migration job fails. When the migration of a pair is canceled, the pair status changes to SMPL, and you can then perform migration again.

Performing post-migration tasks

Delete the volumes and the host group that were created for migration.

The following figure shows the workflow.

Deleting LU paths
Delete the LU paths that were set for the source volumes. Note that the path settings of source volumes and target volumes are switched when migration finishes. For this reason, be sure to delete the paths set for the host group that was created for volume migration (the host group that is not allocated to the host).
Deleting volumes (source volumes)
Delete the source volumes. Note that the LDEV IDs are switched when migration finishes. For this reason, when specifying the LDEV IDs of the volumes to be deleted, be sure to specify the LDEV IDs of the volumes that were created as the target volumes (volumes that do not receive I/O from the host).
Deleting the host group
If the host group to which the source volumes belong is no longer necessary, delete the host group.

Specifying Job-Mode-Wait-Configuration-Change in the request header

With respect to operations to perform or cancel migration, data copying might take a long time. As a result, the job status might not change to Completed and other jobs might become delayed if you execute multiple asynchronous processes at the same time. In such cases, specify Job-Mode-Wait-Configuration-Change:NoWait in the request header, so that the job status changes to Completed without waiting for data copying to finish, and the next job starts. In other words, data copying will continue even after the job execution ends. To check whether data copying has finished, check the status of the applicable pair, instead of checking the job status. For details about pair statuses, see the description of pair status transitions.