[CentOS] block level changes at the file system level?

On Wed, Jul 2, 2014 at 2:53 PM, Lists <lists at benjamindsmith.com> wrote:
> I'm trying to streamline a backup system using ZFS. In our situation,
> we're writing pg_dump files repeatedly, each file being highly similar
> to the previous file. Is there a file system (EG: ext4? xfs?) that, when
> re-writing a similar file, will write only the changed blocks and not
> rewrite the entire file to a new set of blocks?
>
> Assume that we're writing a 500 MB file with only 100 KB of changes.
> Other than a utility like diff, is there a file system that would only
> write 100KB and not 500 MB of data? In concept, this would work
> similarly to using the 'diff' utility...

There is something called rdiff-backup
(http://www.nongnu.org/rdiff-backup/ and packaged in EPEL) that does
reverse diffs at the application level.  If it performs well enough it
might be easier to manage than a de-duping filesystem.    Or backuppc
- which would store a complete copy if there are any changes at all
between dumps but would compress them and automatically manage the
number you need to keep.

-- 
   Les Mikesell
      lesmikesell at gmail.com