Dell PowerVault 720N, Command Reference Manual, Page: 264 / 606

9-12 Dell PowerVault 720N, 740N, and 760N System Administrator and Command Reference Guide
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If the data changes very quickly, reduce the number of snapshots scheduled. For
example, if a volume is filled and emptied each day, for example, a volume storing
large temporary files for a CAD application, it might not make sense to use daily
or weekly snapshots at all.
On a very active volume, schedule snapshots every hour and keep them for just a
few hours, or turn off snapshots. For example, the following schedule creates a
snapshot every hour and keeps three:
snap sched home 0 0 3
This schedule doesn’t consume much disk space, and it lets users recover files in
recent snapshots as long as they notice their mistake within a couple of hours.
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When you create a new volume on a filer, the new volume inherits the snapshot
schedule from the root volume. After you use the volume for a while, check how
much disk space the snapshots consume in the volume.
'LVSOD\LQJ6QDSVKRW6WDWLVWLFV
The
snap list
command shows the amount of disk space used by snapshots in a
specified volume. This command enables you to see how much disk space each snap-
shot uses, and helps you determine an appropriate snapshot reserve.
&RPPDQG2XWSXW
Following is an example of the command output. If you don’t specify a volume name
in the command, the output contains statistics about each volume.
snap list vol0
Volume vol0
%/used %/total date name
---------- ---------- ------------ --------
0% ( 0%) 0% ( 0%) Jan 19 08:01 hourly.0
1% ( 1%) 1% ( 1%) Jan 19 00:01 nightly.0
2% ( 2%) 2% ( 2%) Jan 18 20:01 hourly.1
3% ( 2%) 2% ( 2%) Jan 18 16:01 hourly.2
3% ( 2%) 3% ( 2%) Jan 18 12:01 hourly.3
5% ( 3%) 4% ( 3%) Jan 18 00:01 nightly.1
7% ( 4%) 6% ( 4%) Jan 17 00:00 nightly.2
8% ( 4%) 7% ( 4%) Jan 16 00:01 nightly.3
10%( 5%) 9% ( 4%) Jan 15 00:01 nightly.4
7KH8VHG&ROXPQ
The %/used column shows space consumed by snapshots as a percentage of disk
space being used in the volume. The first number is cumulative for all snapshots
listed so far, and the second number is for the specified snapshot alone.