Hello,
this is probably a bit difficult to understand at first, but I will try
to explain.
Each backup is a full backup, even though only the differences to the
last backup are actually backed up. The remaining unchanged block are
just being referenced from the last backup. When you delete a previous
backup, only those blocks which are not referenced by another backup
will actually be deleted.
So each backup is independent on its own, and you can delete all
previous backups without losing any data.
Hope this clears it up a bit.
Bye,
Andreas
Am 02.03.2021 um 11:22 schrieb mj:
Hi,
Testing PBS backups taken from PVE VMs on ceph rbd now. Very nice,
very quick, very cool. :-)
We have a question. Something we wonder about.
In our current backup software, we make weekly full_system backups,
and daily incremental_system backups, each incremental based on the
same full_system backup. So: each daily incremental backup becomes
bigger, until the weekend. Then we make a new full_system backup to
base the next set of incrementals on.
In PBS I cannot specify if a backup is full or incremental, we assume
this means that automatically the first backup is a full_system
backup, and subsequent backups are incremental. The PBS backup logs
confirm this assumption, saying: "scsi0: dirty-bitmap status: created
new" vs "scsi0: dirty-bitmap status: OK (7.3 GiB of 501.0 GiB dirty)"
And now the question: At what point in time is a new full_system
backup created, to rebase incremental backups on?
Or is each incremental backup based on the previous incremental? And
if that is the case, how will we ever be able to delete one of the
in-between incrementals, because that would then break to whole chain
of incremental_backup-based-on-incremental_backup...?
We have read the page
https://qemu.readthedocs.io/en/latest/interop/bitmaps.html but it does
not seem to answer this.
Anyone care to share some insight on this logic and how PBS works?
MJ
_______________________________________________
pve-user mailing list
[email protected]
https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-user
