[pve-devel] KVM Live Backup performance

[Eric Blevins]

> I just uploaded the qemu 1.7 package with new backup patches:
>
> You should be able to install with:
>
> # wget ftp://download.proxmox.com/tmp/pve-libspice-server1_0.12.4-3_amd64.deb
> # wget ftp://download.proxmox.com/tmp/pve-qemu-kvm_1.7-2_amd64.deb
>
> # dpkg -i pve-libspice-server1_0.12.4-3_amd64.deb pve-qemu-kvm_1.7-2_amd64.deb
>
> Please can you re-run your tests?
>
Same host and guest as before.

Backup command, XXXXX was replaced with various values:
vzdump 108 -stdout|cstream -t XXXXX > /dev/null

Used dd to read in the VM:
dd if=/dev/vdb of=/dev/null bs=1M count=8192 skip=24000

cstream   | dd read  | improvement
140000000 | 128 MB/s |  +19.0 MB/s
120000000 | 130 MB/s |  +34.4 MB/s
100000000 | 129 MB/s |  +48.7 MB/s
80000000  | 129 MB/s |  +63.4 MB/s
60000000  | 135 MB/s |  +87.8 MB/s
40000000  | 140 MB/s | +108.2 MB/s

Used dd to write in the VM:
dd if=/dev/zero of=/dev/vdb bs=1M count=8192 seek=24000

cstream   | dd write
140000000 | 106 MB/s
120000000 | 123 MB/s
100000000 | 125 MB/s
80000000  | 126 MB/s
60000000  | 128 MB/s
40000000  | 123 MB/s

It seems that the backup process is greatly improved, many thanks!