Re: deduplicating file systems: VDO with Debian?
On Tue, 2022-11-08 at 09:52 +0100, DdB wrote:
> Am 08.11.2022 um 05:31 schrieb hw:
> > > That's only one point.
> > What are the others?
> >
> > > And it's not really some valid one, I think, as
> > > you do typically not run into space problems with one single action
> > > (YMMV). Running multiple sessions and out-of-band deduplication between
> > > them works for me.
> > That still requires you to have enough disk space for at least two full
> > backups.
> > I can see it working for three backups because you can deduplicate the first
> > two, but not for two. And why would I deduplicate when I have sufficient
> > disk
> > space.
> >
> Your wording likely confuses 2 different concepts:
Noooo, I'm not confusing that :) Everyone says so and I don't know why ...
> Deduplication avoids storing identical data more than once.
> whereas
> Redundancy stores information on more than one place on purpose to avoid
> loos of data in case of havoc.
> ZFS can do both, as it combines the features of a volume manager with
> those of a filesystem and a software RAID.( I am using zfsonlinux since
> its early days, for over 10 years now, but without dedup. )
>
> In the past, i used shifting/rotating external backup media for that
> purpose, because, as the saying goes: RAID is NOT a backup! Today, i
> have a second server only for the backups, using zfs as well, which
> allows for easy incremental backups, minimizing traffic and disk usage.
>
> but you should be clear as to what you want: redundancy or deduplication?
The question is rather if it makes sense to have two full backups on the same
machine for redundancy and to be able to go back in time, or if it's better to
give up on redundancy and to have only one copy and use snapshots or whatever to
be able to go back in time.
Of course it would better to have more than one machine, but I don't have that.
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