A --exclude-checksum option?

Kevin Korb kmk at sanitarium.net
Tue Feb 12 13:48:35 MST 2013

Hash: SHA1

My first thought is why are you backing up /tmp at all?

My second thought is why are you using atime for anything?  It can be
touched by almost anything and running a filesystem with atime enabled
is a huge performance detriment as it adds a directory write operation
to every file read operation.

My final thought is maybe you want a file verification tool (I like
cfv) instead of rsync --checksum.  Rsync's --checksum is kinda
mindless in terms of performance.  It checksums everything.  This is
rather pointless as a file that is a different size will obviously
have a different checksum.  Rsync even checksums files that only exist
on one side of the transfer.

On 02/12/13 15:42, Karl O. Pinc wrote:
> Hi,
> I use rsync with hardlinks for backup, once a week doing checksums 
> to ensure there's no filesystem corruption in the backed-up data.
> I also use tmpwatch, or something similar, to clean up /tmp, it
> removes files that have not been accessed recently. (atime older
> than some configured limit). I backup /tmp because I throw stuff in
> tmp that I might possibly need again but don't want to bother 
> having to remember to delete -- and if I'm expecting to have useful
> data somewhere I want it backed up.
> However, rsync's checksumming (naturally) updates the atimes of the
> files in /tmp, and so tmpwatch never deletes them.
> It occurs to me that a handy solution might be to have an rsync
> option, similar to the --exclude option, which would allow
> checksumming to happen throughout most of the backup process but 
> would do "regular" size/timestamp based backups on certain
> directories.
> What do people think of such an option? Is there a better design.
> (E.g. an option that, er, preserves atime when checksumming?) Is
> rsync just too overloaded with options already and it would be
> better instead to run two instances of rsync?  Is there a
> bug/feature in process already that would address the use-case 
> above?
> I'd like to have a sensible design before even thinking about
> patching.
> Thanks for the feedback.
> Regards,
> Karl <kop at meme.com> Free Software:  "You don't pay back, you pay
> forward." -- Robert A. Heinlein

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