[pve-devel] qemu 6 : does proxmox backup handle parallel async chunck backup like the new backup code from qemu 6.0 ?

[Thomas Lamprecht]

Hi,

On 02.06.21 08:39, aderumier at odiso.com wrote:
> I was looking for qemu 6.0 new features,
> and it seem that they have implement parallel async chunks backup (and
> I think for other block operations, through a new block-copy feature)
> 
> https://github.com/qemu/qemu/commit/71eed4cebed487a4f3c9f97aba83c611bbe22f8d
> 
> https://github.com/qemu/qemu/commit/de4641b46b020c5b332175f80e8bfe3d352888e8#diff-b33323044f2699244c126c6eae6c4083c3c99a16f4840030ac13238b1f569dc0
> 
> https://github.com/qemu/qemu/commit/26be9d62dd5f5268b814da24fd8e8b5c5b999ebe
> 
> Is it alrealy implemented or on the roadmap for the proxmox backup code
> ?
> (To be honest, I didn't follow proxmox backup patches since a long
> time, so I really don't known how much they are sharing with qemu
> backup code)

the parallel stuff works with our implementation, Stefan tried it and with their
default the backup is much faster, so fast that the guest cannot do anything during
that anymore :D So, IIRC, Stefan turned the default number of parallel operations down
for a better balance of backup speed and guest impact.

FYI, we have basic packages for bullseye as base ready here, and possible sync to
pvetest in the next days/weeks - in those repos there's already QEMU 6.0.

Something else we can use with Bullseye/PVE 7 is io_uring instead of AIO, looks like
a much saner (and actually useful) design and there should be some, at least slight,
improvements due to that too.

https://kernel.dk/io_uring.pdf

cheers,
Thomas