IOERROR: writing cache file

[Bron Gondwana]

On Thu, 27 Sep 2007 16:08:19 +0200, "Rudy Gevaert" <Rudy.Gevaert at UGent.be> said:
> Bron Gondwana wrote:
> > On Thu, Sep 27, 2007 at 02:51:09PM +0200, Rudy Gevaert wrote:
> >> Hello again,
> >>
> >> Does somebody know what could be the source of the following error messages?
> >>
> >> Thu Sep 27 13:24:09 2007 manaslu mail6/imaps/mail6/imaps[27763]: 
> >> IOERROR: writing cache file for ugent.be!user.heleen^nailis.Labo.Rosina: 
> >> Bad address
> >> Thu Sep 27 13:24:26 2007 manaslu mail6/imaps/mail6/imaps[4600]: IOERROR: 
> >> writing cache file for ugent.be!user.heleen^nailis.Labo.Rosina: Bad address
> >> Thu Sep 27 13:26:37 2007 manaslu mail6/imaps/mail6/imaps[15730]: 
> >> IOERROR: writing cache file for 
> >> ugent.be!user.heleen^nailis.maatjes.Gwenn: Bad address
> >> Thu Sep 27 13:26:51 2007 manaslu mail6/imaps/mail6/imaps[2402]: IOERROR: 
> >> writing cache file for ugent.be!user.heleen^nailis.maatjes.Gwenn: Bad 
> >> address
> > 
> > heleen^nailis ?   Is that a carat or a control character being printed?
> 
> That's a carat.
> 
> > Are you able to reproduce reliably?  May be worth trying to grab
> > an strace/truss of the process and see what syscalls it's making.
> 
> I have no idea how it happens.  I just saw it today, a couple of times 
> from the same user.  She has it on two folders. The user has already 
> logged out so I can't attach to that process. :(

Can you log in as the same user and test (or maybe copy the exact
contents of the mailboxes somewhere else and try to recreate - that
is if you care that much to figure out the underlying cause...)

> > Alternatively, you could have filesystem corruption in the meta
> > directories - have you tried moving them aside and creating new
> > ones?
> 
> Hmm.  Do you mean the cyrus.cache file in those folders?  Is a 
> reconstruct enough to recreate them or doesn't happen automatically.

I had a filesystem which had one directory that was totally corrupted
inside due to random gremlins (not sure when it happened, but with
terabytes of storage, these things do happen occasionally, even with
RAID you still get occasional errors on the wire - the research on
this really quite disturbing!)

I moved it out somewhere else and recreated the meta directory then
reconstructed the mailbox.  Worked fine.  You do need to reconstruct
and if you can copy the cyrus.index back in then you'll find that
no information (flags, etc) should be lost.

I failed over to the replica and took the filesystem offline and ran
a full fsck (reiserfsck in this case) which only found the one error
on that folder.  Ran with rebuild-tree to remove it from the tree
(it wasn't deleteable otherwise) and all was good.

And yeah - for pretty much anything involving the cache file,
reconstruct is your friend.  Everything in the cache file is
copies of data in the original messages, so reconstruct can
rebuild it precisely.

Regards,

Bron.
-- 
  Bron Gondwana
  brong at fastmail.fm