Packing problems: fixed

Matt Hamilton <[email protected]>
Newsgroups gmane.comp.web.zope.zodb.dirstorage
Message-ID <[email protected]>
Dear All,
   Just thought I'd share the fix for some packing problems we've been 
having recently in case anyone experiences the same.

We updated a busy zope cluster from 2.6.3 to 2.7.0 several months ago. 
After that time and packs of the DirectoryStorage left us with lots of 
POSKey errors.  Luckily we could just rename all the -deleted files back 
and we were OK.

After many attempts to work out what was wrong, I realised it was a file 
ownership issue.  Under Zope 2.6 our ZEO server ran as user 'zope', but 
under 2.7 it now runs as 'root' (not sure why yet, I guess its to do 
with the different startup procedures from 2.6 and 2.7).

So, all files written by DirectoryStorage *before* the migration were 
owned by 'zope' and the ones *after* were owned by root.  For some 
reason when packing, DirectoryStorage could not mark the files owned by 
'zope' (even though the process was running as root).  And hence it 
ended up removing files in stage 4 that were needed.

The confusing thing was, other than the pack, everything worked fine. 
As the server was run as root it could write new files in the ZODB 
directories fine, and could read the old ones.

Now I have chown'd everything back to root and run the pack, all is 
working fine (and our ZODB is 60% smaller now I have removed several 
months of unwanted history!).  Now I just need to work out why it is 
running as root, get it running as Zope again, and chown the files back.

I guess the main question is: Why did DirectoryStorage not fail during 
the pack if it could not mark/read the files?

FWIW, this is running on FreeBSD 4.10

-Matt

-- 
Matt Hamilton                                       [email protected]
Netsight Internet Solutions, Ltd.        Business Vision on the Internet
http://www.netsight.co.uk                             +44 (0)117 9090901
Web Design | Zope/Plone Development & Consulting | Co-location | Hosting


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