Re: synchronising unison backups

Do you think it is the standard/normal case to try to synchronize backup
copies?  It seems obvious to me (who doesn't use this feature) that the
backup copies should be local only.


Probably not, if you keep just one. That the feature allow you to keep say,
10, means that you can use it to keep a ~10 day work history of changes to
certain files (for me, hand written ones), assuming you sync after each
day, with no extra effort. I've occasionally found that quite useful over
the last 15 years I've done it. For 10 back versions, it's not obvious
where I should find the one I want, so I look both sides.

config is something like this...

backupdir = backup/unison
backup = Regex publications/.(png|jpg|eps)
backup = Regex
.*\.(doc|txt|docx|xlsx|xls|ppt|pptx|pro|ion|html|htm|tex|bib|c|h|cpp|py)
backuplocation = central
backupprefix = $VERSION.
maxbackups = 10
ignore = Path backup/unison

but I have to ignore backup/unison during sync because the files there are
not symmetrical.

Olaf -

Create the copy with unison, take snapshots of the copy on the other
side with rsnapshot. Or use btrfs to create snapshots.


At present, I occasioally rename the backup/unison dir on either side with
the date and machine name so that they enter the general sync. That
probably amounts to the same.

Mike - I use unison to sync different storage at different intervals for
backup as well. This small incremental component is enough for me.


Viv - You're right, but it still pollutes the update messages!


On Fri, 18 Apr 2025 at 20:00, Greg Troxel <[email protected]> wrote:

> Greg Michael <[email protected]> writes:
>
> > This seems like it should be a useful thing to do, but it's difficult to
> > achieve elegantly.
> >
> > 1. backupdir is the same on both sides, but has different contents (each
> > keeps it own history of overwrites). If synchronised directly, the
> version
> > numbers would clash.
>
> I'm having a hard time following what you are doing.   Perhaps include
> the config lines, and then how you are dealing with replica contents.
>
> > 2. Each time a new backup file is created, the filenames are changed for
> > all previous backup versions, leading to a cascade of updates to be
> > propagated.
>
> Do you think it is the standard/normal case to try to synchronize backup
> copies?  It seems obvious to me (who doesn't use this feature) that the
> backup copies should be local only.
>
>
>
> Separately from your question, if what you want is backups rather than
> sync, my take is that unison is the wrong tool, and something like bup
> is better.  (There are other similar tools, e.g. borg, but I'm not
> familiar with them.)
>

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