Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

Use the vxmake cache command to create a cache object on top of the cache

volume that you created in the previous step:

# vxmake [-g diskgroup] cache cache_object \

cachevolname=volume [regionsize=size] [autogrow=on] \

[highwatermark=hwmk] [autogrowby=agbvalue] \

[maxautogrow=maxagbvalue]]

If the region size, regionsize, is specified, it must be a power of 2, and be

greater than or equal to 16KB (16k). If not specified, the region size of the

cache is set to 64KB.

All space-optimized snapshots that share the cache must have a region size

that is equal to or an integer multiple of the region size set on the cache.

Snapshot creation also fails if the original volume’s region size is smaller

than the cache’s region size.

If the region size of a space-optimized snapshot differs from the region size

of the cache, this can degrade the system’s performance compared to the case

where the region sizes are the same.

To grow the cache in size as required, specify autogrow=on. By default,

autogrow=ff.

In the following example, the cache object, cobjmydg, is created over the cache

volume, cachevol, the region size of the cache is set to 32KB, and the autogrow

feature is enabled:

# vxmake -g mydg cache cobjmydg cachevolname=cachevol \

regionsize=32k autogrow=on

Enable the cache object using the following command:

# vxcache [-g diskgroup] start cache_object

For example to start the cache object, cobjmydg:

# vxcache -g mydg start cobjmydg

See “Removing a cache” on page 395.

369Administering volume snapshots

Creating instant snapshots