Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG
2011-10-06 19:30:15
Holger Parplies wrote at about 17:54:05 +0200 on Thursday, October 6, 2011:
> Hi,
>
> Tim Fletcher wrote on 2011-10-06 10:17:03 +0100 [Re: [BackupPC-users] Bad
> md5sums due to zero size (uncompressed) cpool files - WEIRD BUG]:
> > On Wed, 2011-10-05 at 21:35 -0400, Jeffrey J. Kosowsky wrote:
> > > Finally, remember it's possible that many people are having this
> > > problem but just don't know it,
>
> perfectly possible. I was just saying what possible cause came to my mind
> (any
> many people *could* be running with an almost full disk). As you (Jeffrey)
> said, the fact that the errors appeared only within a small time frame may or
> may not be significant. I guess I don't need to ask whether you are *sure*
> that the disk wasn't almost full back then.
Disk was *less* full then...
> To be honest, I would *hope* that only you had these issues and everyone
> else's backups are fine, i.e. that your hardware and not the BackupPC
> software
> was the trigger (though it would probably need some sort of software bug to
> come up with the exact symptoms).
>
> > > since the only way one would know would be if one actually computed the
> > > partial file md5sums of all the pool files and/or restored & tested ones
> > > backups.
>
> Almost.
>
> > > Since the error affects only 71 out of 1.1 million files it's possible
> > > that no one has ever noticed...
>
> Well, let's think about that for a moment. We *have* had multiple issues that
> *sounded* like corrupt attrib files. What would happen, if you had an attrib
> file that decompresses to "" in the reference backup?
>
> > > It would be interesting if other people would run a test on their
> > > pools to see if they have similar such issues (remember I only tested
> > > my pool in response to the recent thread of the guy who was having
> > > issues with his pool)...
> >
> > Do you have a script or series of commands to do this check with?
>
> Actually, what I would propose in response to what you have found would be to
> test for pool files that decompress to zero length. That should be
> computationally less expensive than computing hashes - in particular, you can
> stop decompressing once you have decompressed any content at all.
Actually this could be made even faster since there seem to be 2
cases:
1. Files of length 8 bytes with first byte = 78 [no rsync checksums]
2. Files of length 57 bytes with first byte = d7 [rsync checksums]
So, all you need to do is to stat the size and then test the
first-byte
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- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, (continued)
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Arnold Krille
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Les Mikesell
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Arnold Krille
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Timothy J Massey
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Les Mikesell
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG,
Jeffrey J. Kosowsky <=
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Jeffrey J. Kosowsky
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, John Rouillard
- [BackupPC-users] How to verify Pool (was: Bad md5sums due to zero size...), Christian Völker
- Re: [BackupPC-users] How to verify Pool (was: Bad md5sums due to zero size...), Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Tim Fletcher
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Holger Parplies
- Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Tim Fletcher
Re: [BackupPC-users] Bad md5sums due to zero size (uncompressed) cpool files - WEIRD BUG, Jeffrey J. Kosowsky
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