Nils Breunese (Lemonbit) wrote at about 19:50:35 +0200 on Sunday, October 19,
2008:
> Jeffrey J. Kosowsky wrote:
>
> > When running an incremental backup on my Linux system, BackupPC
> > repeatedly hangs when backing up the mythconverg mysql database for
> > mythtv.
> >
> > Note that the database seems to be perfectly intact and I don't have
> > any problem 'rsyncing' it manually.
> >
> > The specific error messages I get are:
> >
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fpeople.MYI
> > (err=-2, name=var/lib/mysql/mythconverg/people.MYI)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fpidcache.MYD
> > (err=-2, name=var/lib/mysql/mythconverg/pidcache.MYD)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fpidcache.MYI
> > (err=-2, name=var/lib/mysql/mythconverg/pidcache.MYI)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogram.MYD
> > (err=-2, name=var/lib/mysql/mythconverg/program.MYD)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogram.MYI
> > (err=-2, name=var/lib/mysql/mythconverg/program.MYI)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogramgenres.MYD
> > (err=-2, name=var/lib/mysql/mythconverg/programgenres.MYD)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogramgenres.MYI
> > (err=-2, name=var/lib/mysql/mythconverg/programgenres.MYI)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogramrating.MYD
> > (err=-2, name=var/lib/mysql/mythconverg/programrating.MYD)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > fprogramrating.MYI
> > (err=-2, name=var/lib/mysql/mythconverg/programrating.MYI)
> > Can't get rsync digests from
> > /var/lib/BackupPC/pc/consult/3/f%2f/fvar/flib/fmysql/fmythconverg/
> > frecord.MYD
> > (err=-2, name=var/lib/mysql/mythconverg/record.MYD)
> > Can't call method "isCached" on an undefined value at
> > /usr/share/BackupPC/lib/BackupPC/Xfer/RsyncFileIO.pm line 165.
> >
> > It then just proceeds to hang for HOURS...
> >
> > The most disturbing thing to me is that BackupPC seems to be so
> > fragile in that if it encounters a problem, it seems to just hang
> > there (seemingly) forever without sending any error messages
>
> I get error messages about things like network errors BackupPC
> encounters during backups. The error you're having doesn't sound like
> 'regular error' though and that's probably why you get irrgular
> behavior (hanging processes). Either you've hit a bug in BackupPC or
> your installation is broken, but that undefined value error shouldn't
> occur. Did you install BackupPC using a package manager? If so, can
> you verify the installation (e.g. rpm -V BackupPC if you installed an
> RPM)?
Yes - I used yum/rpm under Fedora 8 to install:
BackupPC-3.1.0-3.fc8.noarch.rpm
rpm -V yields no issues (other than a couple of config files that are
now links to edited versions)
Now interestingly, I did a new FULL backup and now subsequent
INCREMENTALS seem to be working. But I will keep monitoring the
situation.
I imagine that either something (maybe the attrib file for that
directory?) was written correctly on the initial full backup (or was
later corrupted though not likely since I'm running RAID and the
backup is fresh). This then caused BackupPC to crash when it hit the
malformed part of the full backup.
Even so, I would still have thought that such errors should either be
RECOVERABLE (e.g., if corresponding folder of previous
full/incremental backup can't be read properly, then just back up any
broken pieces as part of the incremental even if technically the file
hasn't "changed") or the errors should be SIGNALLED and not lead to
hanging or aborting of the backup without appropriate notice (and
explanation) to the end user.
In general, I would think that incrementals should be robust
regardless of how corrupted previous backups are since you can always
just fill in the missing pieces and add them to the incremental.
> > and without even doing something like skipping the troublesome areas
> > and
> > moving on.
>
> Now that would be scary: would you like incomplete backups?
Hmmm --- good question - maybe not....
>
> Nils Breunese.
>
> P.S. Backing up MYI and MYD files of MySQL databases is not very
> useful, as they're not guaranteed to be in a consistent state when you
> back them up. Even if you backed them up succesfully you could have
> corrupt databases after restoring these files. Better create SQL dumps
> using the pre-dump command and backup those.
Yes of course -- but I'm just really doing a root backup of my linux
system and so I am only excluding a few directories rather than being
super fine granular on what to exclude:
$Conf{BackupFilesExclude} = ['/proc/*', '/sys/*', '/selinux/*', '/tmp/*',
'/var/tmp/*']
>
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