Dell PowerVault 720N Command Reference Manual page 258

snap sched vol1 2
Volume name
Create a snapshot every week
and keep a maximum of two.
Create a snapshot every day
and keep a maximum of six.
Create a snapshot every hour,
or at the times listed in the
optional time list and keep a
maximum of eight.
snap sched
snap sched volume_name 0 2 6@8,12,16,20
snap sched volume_name 2 6 8@8,12,16,20
snap sched
6 8@8,12,16,20
snap sched
Optional list of times,
in 24-hour format at
which an hourly snapshot
is created.