HP Veritas Volume Manager 5.0 -UX 11i v3 manual Limitations of online relayout

Understanding Veritas Volume Manager

Online relayout

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Figure 1-30 Example of increasing the stripe width for the columns in a volume

For details of how to perform online relayout operations, see “Performing online relayout” on page 294. For information about the relayout transformations that are possible, see “Permitted relayout transformations” on page 295.

Limitations of online relayout

Note the following limitations of online relayout:

■Log plexes cannot be transformed.

■Volume snapshots cannot be taken when there is an online relayout operation running on the volume.

■Online relayout cannot create a non-layered mirrored volume in a single step. It always creates a layered mirrored volume even if you specify a non- layered mirrored layout, such as mirror-stripeor mirror-concat. Use the vxassist convert command to turn the layered mirrored volume that results from a relayout into a non-layered volume. See “Converting between layered and non-layered volumes” on page 300 for more information.

■Online relayout can be used only with volumes that have been created using the vxassist command or the Veritas Enterprise Administrator (VEA).

■The usual restrictions apply for the minimum number of physical disks that are required to create the destination layout. For example, mirrored volumes require at least as many disks as mirrors, striped and RAID-5 volumes require at least as many disks as columns, and striped-mirror volumes require at least as many disks as columns multiplied by mirrors.

■To be eligible for layout transformation, the plexes in a mirrored volume must have identical stripe widths and numbers of columns. Relayout is not possible unless you make the layouts of the individual plexes identical.

■Online relayout involving RAID-5 volumes is not supported for shareable disk groups in a cluster environment.

■Online relayout cannot transform sparse plexes, nor can it make any plex sparse. (A sparse plex is not the same size as the volume, or has regions that are not mapped to any subdisk.)