Dne 04. 01. 23 v 9:00 Zhiyong Ye napsal(a):
Dear all,
The current standard lv implementation of snapshots is COW (Copy-on-write),
which creates snapshots very quickly. However, the first write performance of
the original lv will be poor after creating a snapshot because of COW.
Moreover, the more snapshots there are, the worse the performance of the
original lv will be.
I tested the random read/write performance when the original lv was created
with different number of snapshots. The data is shown below:
Number of snapshots Randread(iops) Randwrite(iops)
0 21989 22034
1 10048 10041
2 6770 6773
3 5375 5378
There are scenarios where the performance of the original lv is more
demanding, and the speed of snapshot creation is not as strong a requirement.
Because it is the original lv that will actually be used, and the snapshot is
only a secondary function. Therefore snapshots using the COW approach will not
meet the needs of this scenario.
Therefore, is it feasible to implement another way of taking snapshots? Let's
say the first snapshot is created as a full snapshot, and all subsequent
snapshots are based on incremental data from the previous snapshot.
Hi
Have you played with thin provisioning - as that's the answer to the slow
snapshots.
Regards
Zdenek
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