Migrating a VDisk to a new I/O group using the CLI

You can use the command-line interface (CLI) to migrate a virtual disk (VDisk) to a new I/O group to increase the size of your cluster.

You can migrate a VDisk to a new I/O group to manually balance the workload across the nodes in the cluster. However, you might end up with a pair of nodes that are overworked and another pair that are not worked. Follow this procedure to migrate a single VDisk to a new I/O group. Repeat for other VDisks as required.

Attention: This is a disruptive procedure. Access to the VDisk is lost while you follow this procedure. Migration commands fail if the target or source VDisk is offline, or if there is insufficient quorum disk space to store the metadata. Correct the offline or quorum disk condition and reissue the command.

Perform the following steps to migrate a single VDisk:

Quiesce all I/O operations for the VDisk. You might have to determine the hosts that are using this VDisk in advance.
Before migrating the VDisk, it is essential that for each device identifier that is presented by the VDisk you intend to move, the subsystem device driver (SDD) or other multipathing driver configuration is updated to remove the device identifiers. Failure to do this can result in data corruption. See the IBM® System Storage® Multipath Subsystem Device Driver User's Guide or the documentation that is provided with your multipathing driver for details about how to dynamically reconfigure device identifiers for the given host operating system.
Issue the following command to check if the VDisk is part of a relationship or mapping:
```
svcinfo lsvdisk vdiskname/id
```
Where vdiskname/id is the name or ID of the VDisk.
1. Find the FC_id and RC_id fields. If these are not blank, the VDisk is part of a mapping or relationship.
2. Stop or delete any FlashCopy® mappings, Global Mirror, or Metro Mirror relationships that use this VDisk.
Issue the following command to migrate the VDisk:
```
svctask chvdisk -iogrp newiogrpname/id -node preferred_node vdiskname/id
```
where preferred_node is the name of the node that you want to move the VDisk, newiogrpname/id is the name or ID of the I/O group where you want to migrate the VDisk and vdiskname/id is the name or ID of the VDisk that you want to migrate.
Discover the new device identifiers and check that each device identifier presents the correct number of paths. See the IBM System Storage Multipath Subsystem Device Driver User's Guide or the documentation that is provided with your multipathing driver for details about how to discover device identifiers for the given host operating system.