[pve-devel] Speed up PVE Backup

[Stefan Priebe - Profihost AG]

Am 16.02.2016 um 11:55 schrieb Dietmar Maurer:
>> Is it enough to just change these:
> 
> The whole backup algorithm is based on 64KB blocksize, so it
> is not trivial (or impossible?) to change that.
> 
> Besides, I do not understand why reading 64KB is slow - ceph libraries
> should have/use a reasonable readahead cache to make it fast?
> 

OK i found the culprit at least in my case. I've reasanle IOP/s numbers
for my VMs set. It seems they're also active for the backup process.

But they're not optimized for 64k sequential I/O. Also this means the
user has not the full performance while doing backups.

May you have seen the same while testing? If i remove the disk throttle
limits i see around 130MB/s for the vma backup.

Stefan