Qsan Technology P300H61, Руководство пользователя

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5.4 QSnap
Snapshot-on-the-box (QSnap)
captures the instant state of data in the target volume
in a logical sense. The underlying logic is Copy-on-Write -- moving out the data which
would be written to certain location where a write action occurs since the time of data
capture. The certain location, named as “Snap VD”, is essentially a new VD which can be
attached to a LUN provisioned to a host as a disk like other ordinary VDs in the system.
Rollback restores the data back to the state of any time which was previously captured in
case for any unfortunate reason it might be (e.g. virus attack, data corruption, human
errors and so on). Snap VD is allocated within the same RG in which the snapshot is taken,
we suggest to reserve 20% of RG size or more for snapshot space. Please refer to the
following figure for snapshot concept.
Figure 5.4.1
5.4.1 Create snapshot volume
To take a snapshot of the data, please follow the procedures.
1.
Select “/ Volume configuration / Virtual disk” .
2. Check the gray button next to the VD number; click “Set snapshot space” .
3. Set up the size for snapshot. The minimum size is suggested to be 20% of VD size,
and then click “OK” . It will go back to the VD page and the size will show in snapshot
column. It may not be the same as the number entered because some size is
reserved for snapshot internal usage. There will be 2 numbers in
“Snapshot” column.
These numbers mean “Used snapshot space” and “Total snapshot space” .