[pve-devel] KVM Live Backup performance
dietmar at proxmox.com
Mon Nov 25 12:26:10 CET 2013
> I have not tested writes yet and doubt I will have time to get to that this week.
To show drawbacks of LVM snapshots, you can use something like:
# dd if=/dev/urandom of=tmp.raw bs=1M
inside the VM during backup.
LVM snapshot will most likely run full, and is very slow:
# time vmtar ....
ERROR: incomplete read detected
Command exited with non-zero status 255
6.13user 144.59system 21:37.43elapsed 11%CPU (0avgtext+0avgdata 568maxresident)k
129851856inputs+0outputs (0major+180minor)pagefaults 0swaps
Live backup works as expected:
# time vzdump ...
INFO: transferred 68719 MB in 560 seconds (122 MB/s)
INFO: Finished Backup of VM 40000 (00:09:20)
INFO: Backup job finished successfully
Note: it is more than 2 times faster
More information about the pve-devel