User guide

uNAS/tNASUserGuideVersion1.0 Page40

Function: Snapshot definition
This function allows you to define parameters of every snapshot.
You can set:
• Logical Volume, which the snapshot will be taken for.
• Schedule the time of automatic creation of the snapshot, if inactive - only manual snapshot
activation is possible.
• RO - the snapshot will be visible as a write protected disk. The Snapshot function of the
server enables the system administrator to freeze the data content of the volume at a certain
time. From this moment on, the users work on a virtual data volume, all changes to the volume
are stored in a different partition. The storage of all changes is independent of the file-system -
it takes place on block-level. Only when the snapshot is deactivated / removed the changes
are permanently transferred to the actual data volume. Snapshots can be
activated/deactivated manually or automatically.
Please be reasonable, when you are calculating the space reserved for snapshots. Please set
as snapshot size as much space as you expect to change during active snapshot.
E.g. when you are doing backup from snapshot which takes one hour please set this snapshot
size to as much space that will be changed during one hour. The snapshot will become
inactive if the content (data changed on Logical Volume) exceeds the snapshot capacity. You
do not lose data in that case, just the dataset, which is virtual for the users at the moment, will
be written to the data volume. The old dataset, which has been frozen with the snapshot, is not
available any longer. When you define the schedule, use only as many snapshots in the same
time as really needed. A large count of active snapshots can slow down the system
considerably.
Manual creating and removing of snapshots can be done in the SETUP
 volume manager  vg[nr]  Function: Volume Manager.
How to access NAS snapshot
After snapshot has been created and activated, you can access it by following: