Re: [rdiff-backup-users] comments about rdiff-backup

[Keith Edmunds]

Faheem Mitha wrote:
> This predictably means that (since the previous job has not completed) at 
> some point two different instances of rdiff-backup will be running and 
> trying to write to the same directory
.
.
> I wonder whether it would not be possible 
> for rdiff-backup to detect that another rdiff-backup process was writing 
> to the same directory and exit gracefully?

I see this as down to the system administrator to manage, and much 
easier too. For example, suppose I have two backup jobs, one backing up 
user xxx and a second backing up user yyy. Those two backup jobs might 
writing, respectively, to:

        /backups/home/xxx/...
        /backups/home/yyy...

That won't cause a problem at all. Now suppose on your system you backup 
the whole of /home. A second invocation is started, so at one point 
there are two rdiff-backup processes, and they are writing to the 
directories shown above. How should rdiff-backup decide that the former 
pair of processes are safe to run, but the latter pair are not? Yes, it 
can be done by parsing command lines of other processes - but even that 
may not be possible if each of user xxx and yyy are running the backup 
process under their own UIDs.

What I do:

        #!/bin/bash
        # Start of script
        ACTIVE_FLAG=/var/run/backup_in_progress
        [ -e $ACTIVE_FLAG] && exit 1 || touch $ACTIVE_FLAG
        .
        .
        # End of script
        rm $ACTIVE_FLAG

Actually it's a little more sophisticated than that, but you get the idea.

Keith

--
Keith Edmunds

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