All disk groups have a version number associated with them. Each major Veritas Volume Manager (VxVM) release traditionally introduces a disk group version, however, in some cases a new disk group version will not be created for a particular VxVM version.
To support new features, the disk group must be at least the disk group version of the release when the feature was introduced. If you need to import a disk group on a system running an older version of Veritas Volume Manager, you can create a disk group with an earlier disk group version.
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By default, VxVM creates a disk group of the highest version supported by the release.
For example, Veritas Volume Manager 7.4.1 creates disk groups with version 280.
Each VxVM release supports a specific set of disk group versions. VxVM can import and perform operations on a disk group of any supported version. However, the operations are limited by what features and operations the disk group version supports.
Attempts to use a feature of the current version that is not a feature of the version from which the disk group was imported results in an error message similar to this:
VxVM vxedit ERROR V-5-1-2829 Disk group version doesn't support feature
VxVM product functionality is limited by the features and operations the disk group version supports.
To list the version of an imported disk group, use this command:
# vxdg list dgname
You can also determine the disk group version of an imported disk group by using the vxprint command with the -l format option.
To create a disk group with a previous version, specify the -T version option to the vxdg init command.
When you want to use new features, the disk group can be upgraded. The upgrade is an explicit operation. Once the upgrade occurs, the disk group becomes incompatible with earlier releases of VxVM that do not support the new version. There is no "downgrade" facility. For disk groups which are shared among multiple servers for failover or for off-host processing, verify that the VxVM release on all potential hosts that may use the disk group supports the disk group version to which you are upgrading.
To use any of the new features, you must run the vxdg upgrade command to explicitly upgrade the disk group to a version that supports those features.
To upgrade a disk group to the highest version supported by the release of VxVM that is currently running, use this command:
# vxdg upgrade dgname
Until the disk group is upgraded, it can still be imported by other servers supporting the disk group version.