[Unison-hackers] Quick poll: Who uses backup / backups?

[Derek Rayside]

I use the centralized backup facility.  I run a cron job to delete files
out of this directory that are more than 90 days old.  Otherwise the
central backup directory can grow quite large:  it used to get into the
10-20gb range before I would clean it manually, but now the cron job
usually keeps it under 5gb.

Of course, I wouldn't want to delete my working files that are over 90
days old.  But if the names were sufficiently unique then it wouldn't be
too hard to make the cron job delete the backups and not the real files.

Have you considered make a .snapshot or .backup directory inside of each
directory?  We have a file server here that puts a .snapshot directory
inside of each directory.  It contains four hourly snapshots and a week's
worth of nightly snapshots, plus four weekly snapshots.  The server does
this via some copy-on-write facility.  Users are pretty happy with
retrieving old version of their files this way, and it doesn't clutter up
their working directories.

My personal preference is to have a .backup/.snapshot directory inside of
each directory.  Advantages:
- easier to retrieve backups than from a centralized backup directory
- doesn't clutter up working directories like .bak files do
- backups move around when directories get renamed
- still easy to write a cron job to delete old backups without worrying
  about accidentally clobbering the real files

While we're on the subject of the backup feature, it might also be nice to
have Unison run a compression program (eg, gzip, bzip2, infozip, whatever)
on the backup files.  They are rarely accessed, and can grow to consume a
lot of space.

Thanks for writing such a great piece of software.

Derek.


On Mon, 6 Jun 2005, Benjamin Pierce wrote:

> We're in the middle of some reimplementation work on the merge
> functionality, and as part of this we're considering simplifying and
> rationalizing the backup functionality.
>
> At the moment, Unison provides two different preferences for controlling
> backups: "backup", which keeps backup copies in the same directory as the
> current version of the file, and "backups", which maintains a centralized
> tree of backup files under the .unison directory.
>
> We're considering removing the centralized mechanism and keeping just the
> simpler "backup" functionality (and, at the same time, giving the user more
> control over how these backup files are named).
>
> If you would be seriously inconvenienced by this change, can you please
> either drop me an email or (if you have a comment of general interest) post
> a message here?
>
>      - Benjamin
>
>
>
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