[Dirvish] Tips for low-bandwidth backups

Asheesh Laroia asheesh at asheesh.org
Mon Aug 6 09:41:53 UTC 2007


On Mon, 6 Aug 2007, Dave Howorth wrote:

> There used to be a saying that the highest bandwidth link between London
> and Manchester was a van full of tapes. I suspect it's still true. The
> obvious suggestion is to carry the initial image on tape or disk rather
> than use a slow network connection. But if you don't want to do that ...

The initial image is done, it's just that the other site generated a lot 
of data that should get backed up.  Most days there will be a tiny 
differential, but some days there will be a huge differential - so big 
that it could take around a week to push it all up.

>> I can live with these weeks-long connections when necessary, but my
>> question is: How can I get dirvish to not start a new job while the same
>> backup job is already running successfully (albeit slowly)?
>
> There are at least two options:
>
> (1) simplest. Just run the initial dirvish command on the command line
> instead of as a cron job. Only edit the cron file after it's finished:
>
>  dirvish --vault your-vault --init

I did already --init successfully.  The problem is that the system gained 
a whole lot of data in the weeks since that --init, and the dirvish cron 
job wants to do incremental backups (a fine thing to do!), but then it 
starts one at the same time as another and they compete for those lousy 40 
kilobytes per second (a sad thing to do).

> (2) If you really want to use a cron job for some reason, add the
> command to the cron file, wait until it's started running, then comment
> it out of the cron file until it's finished.

That's not very automated!  It's the incremental backups that I'm 
interested in now, not the first init.

-- Asheesh.

--
Bizarreness is the essence of the exotic.


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