Backup scripts - recycling old backup directories

[Brian Cuttler]

I'm using rsync to backup file systems from one machine to another
(not sure why we aren't using amanda like we are everywhere else).

The combination of rsync updating blocks, rather than replacing files
or replicating file systems is a huge savings for us. As daily zfs
snapshots (saved for a day, a week, a month, three months) on the 
receiving end provides a nice recovery window.

On Fri, Sep 12, 2014 at 02:31:47PM +1000, Robert Bell wrote:
> Folks,
> 
> Kevin Korb wrote:
> >Have you considered more advanced methods such as subvolume snapshots
> >provided by ZFS and BTRFS?  At work we were forced to abandon rsync
> >- --link-dest because of the amount of time it takes to delete old
> >backups when the data is primarily many millions of small files
> >(shared web hosting company).
> 
> We don't have more advanced methods like subvolume snapshots available
> to us.
> 
> However, we can recycle backup directories.
> 
> When we started using rsync with --link-dest back in about 2007, we
> deleted old backups, but realised soon after that we could recycle old
> backups.
> 
> With daily backups, we find about 1.5% of the data and 0.5% of the files
> change from one day to the next, so a directory from about 5 days ago
> will typically be only 5-10% wrong and can be recycled to be the target
> of the latest directory - that's a lot better than recreating the whole
> directory tree for a new backup, and then deleting a whole old directory
> tree.
> 
> We use --delete of course.
> 
> Hope this helps someone.
> 
> Rob.
> 
> Dr Robert C. Bell
> HPC National Partnerships | Scientific Computing
> Information Management and Technology
> CSIRO
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   Brian R Cuttler                 brian.cuttler at wadsworth.org
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