Tandberg Data
BakStor Installation and Administration Manual
35
4.4 Snapshots
A snapshot makes it possible to take a point-in-time image of a disk slice. It is not a full copy of
the disk slice, rather it is an image of what the disk slice looked like at the moment the snapshot
was taken. As the original disk slice is modified the snapshot can be used to "go back in time" to
the time the snapshot was taken. A snapshot can be exported and mounted on an iSCSI initiator
computer just like a regular disk slice. The snapshots on a BakStor are both readable and
writeable.
Since the only disk space used by a snapshot is the parts of the slice that has changed on either
the original slice or the snapshot, the snapshot and the original slice share the majority of the
disk space.
However, as the difference between the original slice and the snapshot increases the amount of
space used for the snapshot will increase. If the BakStor runs of space to accommodate the
growth of a snapshot the snapshot will become unavailable. The BakStor will intelligently
allocate space for the snapshot on the RAID sets most suitable.
The BakStor has two methods for Snapshots: Scheduled and Instant
4.4.1 Creating Instant Snapshots
To create an instant snapshot, choose Snapshot ? Create a snapshot
The following information must be provided:
Slice name
. The slice to take a snapshot of.
Snapshot size. This is the amount of disk space the snapshots starts with. The size is
specified as a percentage of the slice to take snapshot of. If taking a snapshot of a disk
slice of size 500GB and 10% is specified 50GB will initially be reserved for the
snapshot.
Snapshot name. If the snapshot name is not defined the slice-name date and time will be
used as the name of the snapshot
Then click the ACCEPT button to create the snapshot.
