[Borgbackup] tag A or U when files are updated ?

[Bzzzz]

On Fri, 3 Sep 2021 15:32:07 +0200
Ernest CHIARELLO <Ernest.Chiarello at univ-fcomte.fr> wrote:

Hi Ernest,

> thank you for taking the time to answer me ! 😁
> 
> I want to clarify my request. we are typically in a case of
> libvirt/kvm virtualization.
> 
> for the moment, i was using borgbackup in order to save VM-images and 
> snaphots from a local backups folder to a repository on a remote 
> server... it works perfectly.
> 
> actually, VM-images are managed by fi-backup 
> <https://github.com/dguerri/LibVirtKvm-scripts/blob/master/fi-backup.sh>, 
> a bash script which produces one snaphot per hour of each VM, and
> which consolidates them at the end of the day into a single qcow2
> file ... then starts again the next day.

Of course, it entirely depends on what you do inside your VMs, but just
one day of snapshots with a reset every evening seems a bit short.

IF there are files that are users (or admins) modified in these VMs, you
can be sure that one day or another, they'll goof just before a long WE
without noticing it at once…

> after each snaphot creation, fi-backup copies the file to the backups 
> folder.when it consolidates all the snapshots (small files), it also 
> copies the new image (big file) to the backups folder.it uses the 
> command "cp -u", which is expensive in time...
> 
> my question is: would it be possible to replace the "cp -u" by "borg 
> create" (from /var/lib/libvirt/images to /var/lib/libvirt/backups), in 
> order to benefit from the deduplication and to shorten the copy times ?

Is there a very good justification to make your backups from copies
instead of originals ?

Jean-Yves