| This window enables you to configure the disk space reserved
for snapshots, specify the number of snapshots to keep, and set the hourly snapshot
schedule. You make changes in this window on a per-volume basis. To select a volume, use
the Volume pull-down menu.
The Reload button reloads the current settings from the filer. The Save button saves
your changes to the filer.
The following list describes the fields in this window:
- Snapshot Reserve
- Specifies the percentage of disk space that only snapshots can use. The filer cannot use
the reserved space for the active file system. Using the snapshot reserve offers this
advantage: If the active file system is at 100%, deleting files from the active file
system frees disk space because the deletion causes additional disk space to be consumed
only in the disk space reserved for snapshots. If you do not have a snapshot reserve,
deleting files in the active file system does not free disk space because after the
deletion, the amount of disk space that was used by these files is consumed by the
snapshot.
- NOTE: If snapshots use all of the snapshot reserve at the time when the
active file system is full, you cannot free disk space by deleting files from the active
file system. That is because the same disk space used by the deleted files is to be used
by snapshots. In this situation, you cannot create new files in the active file system
until you free disk space by deleting snapshots.
- Number of weekly, nightly, and hourly snapshots to keep
- Specifies the number of weekly, nightly, and hourly snapshots to keep. The following
list describes when the different snapshots are taken:
- Weekly snapshots are taken at 24:00 on Sunday.
- Nightly snapshots are taken at 24:00 every day.
- Hourly snapshots are taken every hour unless specified otherwise using the hourly
snapshot schedule in this window.
- The filer creates only one snapshot at a time. For example, when it is creating the
weekly snapshot at 24:00 Sunday, it does not create the hourly or nightly snapshot at that
time.
- The following list provides guidelines about how to decide the number of snapshots to
keep:
- If users rarely lose files or typically notice lost files right away, use the default
snapshot schedule.
- If users commonly lose files and need to restore them, delete the snapshots less often
than specified by the default schedule. For file systems that change very quickly, reduce
the number of snapshots scheduled. For example, if the entire file system on a filer is
filled and emptied each day (for example, a file system 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 system, schedule snapshots every hour and keep them for just a few hours.
- Hourly snapshot schedule
- Specifies the time at which the hourly snapshots are taken. If no times are specified,
the snapshots are taken at each hour.
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