[pve-devel] KVM Live Backup performance

[Eric Blevins]

> No, it is hard coded and quite small.
>
> But that mbuffer looks promising - maybe we can use much larger
> buffers (same size as LVM snapshot size), maybe mmap'ed?
To clarify, are you are suggesting to make the existing hard coded 
buffer larger/configurable?
If so, I like this idea. It seems like the most IO efficient way to 
perform the backup while having the least impact on the guest IO 
performance.

The LVM snapshot size and buffer size should be two different settings 
since snapshots are still used for openvz.  The settings should be 
configurable in the same manner.

The host OS storage might be slower than the VMs backing storage.
With a memory mapped file this could make the problem worse in some 
instances.

> Would be great if you can run a few test with such setups.
>
Let me know if you need something tested.