[ZODB-Dev] Recovering Corrupt Database

[Tino Wildenhain]

Hi Cody,

I know, this does not help you at the moment,
but you plan to backup now on a regular basis,
dont you?

Backup is easy for Data.fs - just copy it to somewhere else
even when zope is running. cron and bzip2 is your friend :)

Regards
Tino

--On Mittwoch, 30. Oktober 2002 02:53 -0800 Cody Smith 
<smithcc@uclink.berkeley.edu> wrote:

> We're running Zope 2.3.2, and haven't really had any problems with the
> back end (which is my business, instead of the marketing team's
> business), so I haven't had to fret over it recently.  Quite sadly, our
> zope server suffered from some disk problems recently, and we lost a
> chunk of data in the _middle_ of our Data.fs, and now Zope refuses to
> start.  We get this error message:
>
> zope# ./start
> 2002-10-30T10:37:40 PANIC(300) z2 Startup exception
> Traceback (innermost last):
>   File /opt1/Zope-2.3.2-src/z2.py, line 566, in ?
>   File <string>, line 1, in ?
>   File /opt/Zope-2.3.2-src/lib/python/Zope/__init__.py, line 110, in ?
>   File ../lib/python/ZODB/FileStorage.py, line 308, in __init__
>     (Object: /opt1/Zope-2.3.2-src/var/Data.fs)
>   File ../lib/python/ZODB/FileStorage.py, line 1674, in read_index
>   File ../lib/python/ZODB/FileStorage.py, line 219, in panic
> CorruptedTransactionError: /opt1/Zope-2.3.2-src/var/Data.fs data record
> exceeds transaction record at 300605488L
>
> At this point, I find the fsrecovery script and run it.  Unfortunately,
> it, like the start script, fails.
>
> zope# python lib/python/ZODB/fsrecover.py var/Data.fs
> Traceback (innermost last):
>   File "lib/python/ZODB/fsrecover.py", line 94, in ?
>     FileStorage.recover(sys.argv[1])
>   File "lib/python/ZODB/FileStorage.py", line 1542, in recover
>     file.truncate(npos)
> NameError: npos
>
> Now I'm forced to look at the script myself to see why this is happening,
> and I note that, in the script, the last few lines before the error look
> like this:
>
>     if pos < sz:
>         npos = shift_transactions_forward(
>             index, vindex, tindex, file, pos, opos,
>             )
>
>     file.truncate(npos)
>
> Now it makes sense: if pos >= sz, npos is undefined.  So I add in a
> debugging line and find that pos = 406821544 and sz = 406821544.  After
> that, I add an else clause to set npos=opos (or was it pos, I don't
> exactly remember), that takes 100MB of the size of Data.fs and rolls my
> database back to summer 2001 (angering the marketing team, who insist
> that my job isn't done).  Now I'm stuck, but it seems to me based on the
> first error message that I could probably fix the problem by correcting
> either the broken transaction record or the broken data record (which is
> actually broken, I'm not sure), or both.  Would this help?  Is there
> anything I can do to recover the database?
>
> Thank you _so_ much, if I don't fix this, the marketing team will
> literally have lost a years worth of work, and no one will be happy.
>
> Cody
>
>
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