Re: [rdiff-backup-users] keeping hard-linked copy while backup in progress

[Dave Kempe]

Michael wrote:
> Hi,
> I'm very new to rdiff-backup. I read a few places that if backup 
> process is interrupted while in progress, the backup folder may be 
> corrupted. Since every older version depend on the mirror copy, 
> basically all the increments become useless. Have I got it right so far?
Hi Michael,
no, thats not quite correct - the increments are reverse differentials, 
and rdiff-backup handles each backup atomically, so if the backup is 
interrupted for any given backup run, then the changes in files that are 
relevant to that backup (the files that have changed or been added etc) 
are effectively lost on the destination. This is because rdiff-backup 
rolls the backup back to the last known good state on the next run if 
the previous run was interrupted - it calls this 'regresssing destination'.

The only time I have lost all the increments and have them become 
useless is when the filesystem on the destination is corrupted and files 
go missing at random or get messed up somehow. Depending on what gets 
corrupted, this can lose you all your increments. Its happened enough 
that at a couple of places that I also rdiff-backup the rdiff-backup 
repositories to another location/server. This is useful for disaster 
recovery etc as well of course - in the case of the backup server dieing.

dave