[PVE-User] Proxmox Backup Server (beta)

Thomas Lamprecht t.lamprecht at proxmox.com
Fri Jul 10 16:15:02 CEST 2020

On 10.07.20 16:06, Roland wrote:
> i think there may be a misunderstanding here or i was not clear enough
> to express what i meant.
> i guess in terms of backup storage,  pbs is doing similar to what
> borgbackup does - so indeed that IS i/o and storage effient , but that
> refers to the backup target side.
> but what about the backup source?
> I was referring to VMware cbt as that is a means of avoiding I/O on the
> VM storage, i.e. the backup source.
> afaik, proxmox/kvm does not (yet) have something like that !?

Proxmox Backup Server and Proxmox VE supports tracking what changed with
dirty-bitmaps, this avoids reading anything from the storage and sending
anything over the network that has not changed.

> I you have lot's of terabytes of VM disks, each incremental backup run
> will hog the VMs storage (the same like full backup).
> In VMware, this is adressed with "changed block tracking", as a backup
> agent can determine which blocks of a VMs disks have changed between
> incremental backups, so it won't need to scan through the whole VMs
> disks on each differential/incremental backup run.

see above, we effectively support both - deduplication to reduce target
storage impact and incremental backups to reduce source storage and
network impact.


> see:
> https://kb.vmware.com/s/article/1020128
> https://helpcenter.veeam.com/docs/backup/vsphere/changed_block_tracking.html?ver=100
> i don't want to criticize proxmox, i think proxmox is fantastic, i just
> want to know what we get ( and what we don't get).

No worries, no offense taken ;)


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