Re: deduplicating file systems: VDO with Debian?
On Wed, 2022-11-09 at 14:22 +0100, Nicolas George wrote:
> hw (12022-11-08):
> > When I want to have 2 (or more) generations of backups, do I actually want
> > deduplication? It leaves me with only one actual copy of the data which
> > seems
> > to defeat the idea of having multiple generations of backups at least to
> > some
> > extent.
>
> The idea of having multiple generations of backups is not to have the
> data physically present in multiple places, this is the role of RAID.
>
> The idea if having multiple generations of backups is that if you
> accidentally overwrite half your almost-completed novel with lines of
> ALL WORK AND NO PLAY MAKES JACK A DULL BOY and the backup tool runs
> before you notice it, you still have the precious data in the previous
> generation.
Nicely put :)
Let me rephrase a little:
How likely is it that a storage volume (not the underlying media, like discs in
a RAID array) would become unreadble in only some places so that it could be an
advantage to have multiple copies of the same data on the volume?
It's like I can't help unconsciously thinking that it's an advantage to have
several multple copies on a volume for any other reason than not to overwrite
the almost complete novel. At the same time, I find it difficult to imagine how
a volume could get damaged only in some places, and I don't see other reasons
than that.
Ok, another reason to keep multiple full copies on a volume is making things
simple, easy and thus perhaps more reliable than more complicated solutions. At
least that's an intention. But it costs a lot of disk space.
Reply to: