Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Figure 8-4

Example of storage allocation used to create a mirrored-stripe

volume across controllers

Controllers

Striped plex

Mirror

c1 c2 c3

column 1 column 2 column 3

Striped plex

column 1 column 2 column 3

c4 c5 c6

Mirrored-stripe volume

There are other ways in which you can control how vxassist lays out mirrored

volumes across controllers.

See “Mirroring across targets, controllers or enclosures” on page 319.

Creating a mirrored volume

A mirrored volume provides data redundancy by containing more than one copy

of its data. Each copy (or mirror) is stored on different disks from the original

copy of the volume and from other mirrors. Mirroring a volume ensures that its

data is not lost if a disk in one of its component mirrors fails.

A mirrored volume requires space to be available on at least as many disks in the

disk group as the number of mirrors in the volume.

If you specify layout=mirror, vxassist determines the best layout for the

mirrored volume. Because the advantages of the layouts are related to the size of

the volume, vxassist selects the layout based on the size of the volume. For

smaller volumes, vxassist uses the simpler mirrored concatenated (mirror-concat)

layout. For larger volumes, vxassist uses the more complex concatenated mirror

(concat-mirror) layout. The attribute stripe-mirror-col-split-trigger-pt controls

the selection. Volumes that are smaller than stripe-mirror-col-split-trigger-pt are

created as mirror-concat, and volumes that are larger are created as concat-mirror.

By default, the attribute stripe-mirror-col-split-trigger-pt is set to one gigabyte.

The value can be set in /etc/default/vxassist. If there is a reason to implement

311Creating volumes

Creating a mirrored volume