[CentOS] use of hard links and diff in rsync

On 2013-01-12, ken <gebser at mousecar.com> wrote:
> On 01/11/2013 07:08 PM Reindl Harald wrote:
>> ....
>> different versions of the backup
>> daily, weekly, monthly
>
> Ah, yes, in that kind of scenario hard links would be useful.
>
>> unchanged files are replaced with hard-links
>> the destination files are virtually on the same place
>
> And so then could changes to a file be recorded in the daily version as 
> a diff against the weekly?

Not with rsync or rsnapshot.  If you make a change in one line to a 48GB
file, rsnapshot will remove the appropriate hard link (leaving the
others alone) and create a new 48GB file at a new inode.  (Because
rsnapshot uses rsync, the data transfer for this change is still fast,
but it's still 2x storage.)

--keith

-- 
kkeller at wombat.san-francisco.ca.us