Migrating a VDisk between I/O groups using the CLI

Ensure that you are familiar with migrating a virtual disk (VDisk) between I/O groups.

Attention:

These migration tasks are disruptive. The cached data that is held within the cluster must first be written to disk before the allocation of the VDisk can be changed.
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.

Modifying the I/O group that services the VDisk cannot be done concurrently with I/O operations. It also requires a rescan at the host level to ensure that the multipathing driver is notified that the allocation of the preferred node has changed and the ports by which the VDisk is accessed has changed. This should only be done in the situation where one pair of nodes has become over utilized.

Perform the following steps to migrate a VDisk between I/O groups:

Synchronize all file systems that are mounted on the given VDisk.
Stop all I/O operations to the VDisk.
Issue the following CLI command to migrate the VDisk into a new I/O group:
```
svctask chvdisk -iogrp iogrp_name_or_id -node preferred_node vdisk
 
```
where iogrp_name_or_id is the name or ID of the I/O group that you want to migrate the VDisk to, preferred_node is the name of the node that you want to move the VDisk to, and vdisk is the name of the VDisk that you want to migrate.
Resynchronize the VDisk to host mapping. See the IBM® System Storage® Multipath Subsystem Device Driver User's Guide or the documentation that is provided with your multipathing driver for more information.
Restart the I/O operations to the VDisk.