seen db

[Rudy Gevaert]

Bron Gondwana wrote:

> Try a 2.6.20 kernel, just for an interesting datapoint.  We changed
> back to 2.6.20 (64 bit still) and haven't seen a corrupted seen file
> since.

I hope to try that still today.

I'm now running on 2.6.24-2, 32bit.  I have cleaned up the users that 
were having a corrupted mailbox on replica.  Surprisingly I can count 
them on both hands.

So now I'm again running with rolling replication and I'm doing a 
sync_client session for each user.  When that is finnished I'll try to 
downgrade the kernel.

Btw, I tested my sarge-> etch upgrade in a xen virtual machine, 64bit 
kernel + 32 bit userspace.  But this was 2.6.18.

I'm still wondering if I should run 2.6.20 in 32bit or 64bit...

>>> Oh - can you tell me.  Did the file checkpoint sometime not too long before it
>>> got corrupted?
>> The cases I saw it did.
> 
> Ditto here.  Interesting.  They also had quite long records, but
> I don't know how common that is.  Lots of little bits of seen
> spread around the space.

I'm not sure how I would see that?  I'm not familiar with the internals 
of skiplist.

>>> I've got a small set of theories, but I'm reading the skiplist source code
>>> (again!) to see if they make sense...
>>>
>>> Bron.
>> I'm also wondering if what would happen if I brought up a master. Surely 
>> the imap processes would also segfault.  Right?
> 
> If it was on those corrupted files, yes.  On that machine - quite
> probably.  If you can afford the hardware it may be worth testing.
> 
> (hmm, I can possibly dedicate a 64 bit capable machine to testing
> this.  If it's a kernel bug I'd love to reproduce it)
> 
>> Here I can delete the mailbox on the replica and sync again.  As a  
>> reconstruct doesn't help.
> 
> We find reconstructing helps now - but that's with the 2.6.20
> kernel.  There were multiple things going wrong before.  We
> originally suspected the external drive unit was playing up,
> but I'm thinking kernel now.


Thanks very much for you input!


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Rudy Gevaert          Rudy.Gevaert at UGent.be          tel:+32 9 264 4734
Directie ICT, afd. Infrastructuur ICT Department, Infrastructure office
Groep Systemen                    Systems group
Universiteit Gent                 Ghent University
Krijgslaan 281, gebouw S9, 9000 Gent, Belgie               www.UGent.be
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