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

[John R Pierce]

On 7/2/2014 12:53 PM, Lists 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...

you do realize, adding/removing or even changing the length of a single 
line in a block of that pg_dump file will change every block after it as 
the data will be offset ?

may I suggest that instead of pg_dump, you use pg_basebackup and WAL 
archiving...  this is the best way to do delta backups of a sql database 
server.



-- 
john r pierce                                      37N 122W
somewhere on the middle of the left coast