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

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

About this task

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

If there are any host mappings for the volume, the hosts must be members of the target I/O group or the migration fails.

Perform the following steps to migrate a single volume:

Procedure

  1. Quiesce all I/O operations for the volume. You might have to determine the hosts that are using this volume in advance.
  2. Remove the applicable device identifiers before migrating the volume. For each device identifier that is presented by the volume that you intend to move, the subsystem device driver (SDD) or other multipathing driver configuration must be updated to remove the device identifiers. Failure to do the update can result in data corruption. See the IBM® 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 specified host operating system.
  3. Issue the following command to check whether the volume is part of a relationship or mapping: 
    lsvdisk volume_name

    Where volume_name is the name of the volume.

    1. After the command completes, verify that the volume is not used in any FlashCopy mappings or remote-copy relationships. Find the FC_id and RC_id fields in the results. If these fields are not blank, the volume is part of a mapping or relationship. The value in these fields indicates the ID of the mapping or relationship that must be stopped and deleted before moving the volume to another I/O group.
    2. Stop and delete any FlashCopy® mappings, Global Mirror, or Metro Mirror relationships that use this volume.
  4. Issue the following command to migrate the volume: 
    movevdisk -iogrp iogrp_name -node node_name vdisk_name

    where iogrp_name is the name of the I/O group that you want to move the volume to, node_name is the name of the node for the volume, and vdisk_name is the name of the volume that you want to migrate.

  5. Discover the new device identifiers and check that each device identifier presents the correct number of paths. See the IBM 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 specified host operating system.

    For Fibre Channel attached hosts, check that the zoning allows the host to see the node ports in the target I/O group.

    For Internet Small Computer System Interface (iSCSI) attached hosts the:
    • Hosts must have connectivity to the same Internet Protocol (IP) subnets as the target nodes
    • Target nodes must be configured with iSCSI IP addresses
    • Hosts must be reconfigured to establish iSCSI sessions with the nodes in the target I/O group