[Duplicity-talk] Re: Can one safely run multiple instances to thesame target?

[Eric B.]

> Peter Schuller wrote:
> >> sometimes i have remote clients that will dump a lot of data to backup 
> >> and
> >> will sometimes not finish the backup until after the next daily cron 
> >> job
> >> starts and then i'll have another instance working the same
> >> directories/target. so being able to keep that from happening would be 
> >> a
> >> great benefit.
> >
> > Any objections to implementing a simple mkdir() based lock in
> > duplicity itself? I say mkdir() because it tends to be extremely
> > portable under even pretty wonky circumstances.
>
> No objections here.  At least on UNIX and variants, mkdir is supposed to
> be an atomic action, or at least it used to be.


There would definitely need to be a way to recover from an orphaned 
lockfile.  Additionally, if you are considering adding semaphore ability 
within duplicity itself, it might be an interesting thought to consider 
adding in a --verify-after-backup option to verify within the same duplicity 
execution.  ie: you would not want another instance of duplicity to be able 
to grab the lock prior to being able to do a verify after the backup is 
complete.

At least, that's the way I would see it.

Tx,

Eric