Fabian Cenedese wrote: > At 15:15 18.09.2007 -0400, Matt McCutchen wrote: > >On 9/18/07, Fabian Cenedese <[EMAIL PROTECTED]> wrote: > >> I was wondering what happens if a file that is regularly > synched but > >> seldom changes gets corrupted in the copy. > > > >Are you referring to rsync writing corrupted data to the destination > >file or a problem with the destination filesystem or disk causing the > >file to read as data different from what was written? > > I was thinking of any problem, even a transport error. > > >> There's also the -I, --ignore-times switch. If I use this > but without -c > >> what method is used for checking then? Or does -I imply -c? > > > >-I rewrites the destination file no matter what, while -c > computes its > >MD4 or MD5 checksum first and then rewrites it only if its checksum > >differs from that of the source file. Either option gives the same > >end result for the destination file. However, they may have > different > >performance (-c uses more disk reading but potentially less disk > >writing and slightly less network traffic), and -I logs more > transfers > >than -c and interferes with --link-dest. > > Thanks for the explanations. That means that -l and -c are not > usable together as they contradict themselves, right? > > I was asking because I'm responsible for our backups. The > current solution with rsync works nicely. While the RAID storage > also monitor the HD's SMART state I was still wondering > about a way to detect otherwise unknown data corruption. > > I guess if I first made a normal rsync and then a rsync --dry-run -c > I could find file differences that shouldn't be (provided there > wasn't any real change otherwise, like in the middle of the night). > Of course that wouldn't tell me what side had changed, but still > something worth considering doing once a month or so... > > Thanks for your help > > bye Fabi > Seems like an old sailors rule: Have one chronograph or three, never two. With two, you know something is wrong, but no idea what to do.
Disk is cheap. Thanks for the idea of the rsync --dry-run -c Methinks it will help a lot of Windows users. (even with only two comparands) -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
