Upgrading a Disk Group

Prior to the release of VERITAS Volume Manager 3.0, the disk group version was automatically upgraded (if needed) when the disk group was imported.

From release 3.0 of VERITAS Volume Manager, the two operations of importing a disk group and upgrading its version are separate. You can import a disk group from a previous version and use it without upgrading it.

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.

Before the imported disk group is upgraded, no changes are made to the disk group to prevent its use on the release from which it was imported until you explicitly upgrade it to the current release.

Until completion of the upgrade, the disk group can be used "as is" provided there is no attempt to use the features of the current version. 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:

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.

All disk groups have a version number associated with them. VERITAS Volume Manager releases support a specific set of disk group versions. VxVM can import and perform operations on a disk group of that version. The operations are limited by what features and operations the disk group version supports.

The table, Disk Group Version Assignments, summarizes the VERITAS Volume Manager releases that introduce and support specific disk group versions:

Disk Group Version Assignments

Importing the disk group of a previous version on a VERITAS Volume Manager system prevents the use of features introduced since that version was released. The table, Features Supported by Disk Group Versions, summarizes the features that are supported by disk group versions 20 through 120:

Features Supported by Disk Group Versions

To list the version of a disk group, use this command:

You can also determine the disk group version by using the vxprint command with the -l format option.

To upgrade a disk group to the highest version supported by the release of VxVM that is currently running, use this command:

By default, VxVM creates a disk group of the highest version supported by the release. For example, VERITAS Volume Manager 4.1 creates disk groups with version 120.

It may sometimes be necessary to create a disk group for an older version. The default disk group version for a disk group created on a system running VERITAS Volume Manager 4.1 is 120. Such a disk group cannot be imported on a system running VERITAS Volume Manager 2.3, as that release only supports up to version 40. Therefore, to create a disk group on a system running VERITAS Volume Manager 4.1 that can be imported by a system running VERITAS Volume Manager 2.3, the disk group must be created with a version of 40 or less.

To create a disk group with a previous version, specify the -T version option to the vxdg init command. For example, to create a disk group with version 40 that can be imported by a system running VxVM 2.3, use the following command:

This creates a disk group, newdg, which can be imported by VERITAS Volume Manager 2.3. Note that while this disk group can be imported on the VxVM 2.3 system, attempts to use features from VERITAS Volume Manager 3.0 and later releases will fail.