Am 08.01.2013 08:55, schrieb Alan McKinnon: > On Tue, 08 Jan 2013 08:27:51 +0100 > Florian Philipp <li...@binarywings.net> wrote: > [...] >> >> As I said above, the point is that I need to detect the error as long >> as I still have a valid backup. Professional archive solutions do >> this on their own but I'm looking for something suitable for desktop >> usage. > > rsync might be able to give you something close to what you want > easily > > Use the -n switch for an rsync between your originals and the last > backup copy, and mail the output to yourself. Parse it looking for ">" > and "<" symbols and investigate why the file changed. > > This strikes me as being a very easy solution that you could use > reliably with a suitable combination of options. > >
Hmm, good idea, albeit similar to the `md5sum -c`. Either tool leaves you with the problem of distinguishing between legitimate changes (i.e. a user wrote to the file) and decay. When you have completely static content, md5sum, rsync and friends are sufficient. But if you have content that changes from time to time, the number of false-positives would be too high. In this case, I think you could easily distinguish by comparing both file content and time stamps. Now, that of course introduces the problem that decay could occur in the same time frame as a legitimate change, thus masking the decay. To reduce this risk, you have to reduce the checking interval. Regards, Florian Philipp
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