Snapshots 9-7
The following list shows the snapshots that are created by this snapshot schedule in
1998 (when January 11 is a Sunday):
% ls -lu .snapshot
total 64
drwxrwsrwx 2 root 4096 Jan 14 12:00 hourly.0
drwxrwsrwx 2 root 4096 Jan 14 08:00 hourly.1
drwxrwsrwx 2 root 4096 Jan 13 20:00 hourly.2
drwxrwsrwx 2 root 4096 Jan 13 16:00 hourly.3
drwxrwsrwx 2 root 4096 Jan 13 12:00 hourly.4
drwxrwsrwx 2 root 4096 Jan 13 08:00 hourly.5
drwxrwsrwx 2 root 4096 Jan 12 20:00 hourly.6
drwxrwsrwx 2 root 4096 Jan 12 16:00 hourly.7
drwxrwsrwx 2 root 4096 Jan 14 00:00 nightly.0
drwxrwsrwx 2 root 4096 Jan 13 00:00 nightly.1
drwxrwsrwx 2 root 4096 Jan 12 00:00 nightly.2
drwxrwsrwx 2 root 4096 Jan 10 00:00 nightly.3
drwxrwsrwx 2 root 4096 Jan 09 00:00 nightly.4
drwxrwsrwx 2 root 4096 Jan 08 00:00 nightly.5
drwxrwsrwx 2 root 4096 Jan 11 00:00 weekly.0
drwxrwsrwx 2 root 4096 Jan 04 00:00 weekly.1

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This schedule keeps the eight most recent hourly snapshots, created at 8 a.m., noon,
4 p.m., and 8 p.m. every day, the six most recent daily snapshots, and the two most
recent weekly snapshots. Whenever the filer creates a new snapshot of a particular
type, it deletes the oldest one and renames the existing ones. On the hour, for exam-
ple, the filer deletes hourly.7, renames hourly.0 to hourly.1, and so on. The nightly
snapshot schedule jumps from January 12 to January 10 because there is a weekly
snapshot on January 11.
NOTE: On a UNIX client, if you use ls -l instead of ls -lu to list the snapshot
creation times, the times are not necessarily all different. The times listed by
ls -l
reflect the modification times of the directory at the time of each snapshot, and are
not related to the times at which the snapshots are created.
The snap sched command is persistent across reboots. There is no need to put the
command in the /etc/rc file.
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You can create snapshots at predefined times instead of using the hourly, daily, and
weekly schedules.