LXC Containers Backing Up Incredibly Slow

@fabian If You got >10 milions files rsync doesn't work well (with expected performance - any file-based-tool won't).

Default storage agnostic procedure is OK - but for ZFS we got much more better options.

If we use ZFS on both sides:
- Proxmox->PBS for backup,
- PBS->Proxmox for backup restore,
- Proxmox->Proxmox for Move Storage.

We could use ZFS native tools like 'zfs send' for backup and storage migration between pools/hosts.
Performance profits are not 5% or 10% but 300-500% in many cases so it's worth implementing.
 
@yarii dude, I gave up on advising zfs specific tools to proxmox chaps. "You can't make somebody change the opinion that they have convinced them self into". ATM only answer given is "give it more hardcore nvme hyper-high iop storage and cpu to boot".


as a side note, I honestly still can't understand what is so complex with this work flow:

1. pve asks pbs to start backup session
2. pve tells pbs that it's container / vm is on storage X / Y / Z
- pbs has same storage X - continues with X optimised backup snapshot
- pbs has same storage Y - continues with Y optimised backup snapshot
- pbs has same storage Z - continues with Z optimised backup snapshot
- pbs and pve storage are not matching - falls back to default "agnostic backup strategy"
3 ....
4. profit.
 
I clearly understand the concept of being agnostic and agree this approach.
But from other side: Proxmox recommends ZFS - so IMO work with ZFS should be done with native ZFS tools.