skiplist db corruption
Sergio Devojno Bruder
bruder at haxent.com.br
Mon Nov 13 12:20:49 EST 2006
Ken Murchison wrote:
> Robert Mueller wrote:
>> Just reviving an old issue to see if anyone has any more information.
>> We still see this every now and then, most often with seen state
>> databases. It's most often after an unclean shutdown, but I've seen
>> it at other times as well. Has anyone got any more ideas on what
>> might be causing this?
> We haven't seen this locally, so it hasn't risen to the top of my
> queue yet.
We've seen corruption caused by 2 diferent sources:
- fail on allocation of memory: linux can negate mmap's with plenty of
memory free. There was a patch to use remap instead of unmap / mmap
again, but we never tested it;
- there is some sort of race, that shows up in (real) smp boxes (dont
count HT in smp);
We "solved" it by a) adding memory (now our mupdate server has 4G) and
b) using an UP linux kernel. Wimpy, but worked. After that "solutions"
we hasnt seen a corruption for almost an year.
To put things in perspective:
[root at mupdate ~]# /usr/lib/cyrus-imapd/ctl_mboxlist -d | wc -l
[root at mupdate ~]# free
total used free shared buffers cached
Mem: 3980680 3127804 852876 0 85612 2767608
-/+ buffers/cache: 274584 3706096
Swap: 2096472 144 2096328
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