Re: [CentOS] use of hard links and diff in rsync

On 2013-01-12, ken gebser@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