[Dovecot] error in 1.1.2

[Timo Sirainen]

On Tue, 2008-09-09 at 17:31 +0200, Cor Bosman wrote:
> > 60 seconds is also when Dovecot decides the dotlock file is stale. So I
> > guess the cache file compression is taking longer than that. Hmm. I
> > hadn't thought about that before, since it was supposed to happen rarely
> > enough. But I guess during the compression other processes shouldn't be
> > stuck waiting for it. I'll have to think about something - probably make
> > the lock timeout only a couple of seconds and after that just fail to
> > update it.

Did a couple of changes:

http://hg.dovecot.org/dovecot-1.1/rev/898e3810c014
http://hg.dovecot.org/dovecot-1.1/rev/e3c5acf92b53

> > But the cache compression really shouldn't take that long unless you're
> > really really running out of disk I/O. I wonder if there's some problems
> > with the locking / NFS caching. You do have mail_nfs_*=yes, right?
> 
> # grep nfs dovecot.conf
> mail_nfs_storage = yes
> mail_nfs_index = yes
> 
> What exactly is being compressed? We have 500MB mailspace, and plenty of
> users have that kind of space actually in use. 

Basically deleted space is removed from dovecot.index.cache by
recreating the file and leaving out the deleted parts.

> I dont think the storage servers are slow in any way. Else we'd be seeing
> this much more. As i said, so far it's less than 1% of our users that I can
> find with that cache error, but most of those do say they have a lot of large
> files. So maybe it's something with lots of emails, and the need to update
> a large portion of the cache? It probably needs to go over the wire twice
> right? Once to read, once to write?

You could check how large the dovecot.index.cache file is for those
users. Normally it's something like 10-20% of the mailbox size, but it
really depends on the emails.

> One thing is, we dont use deliver, so whenever dovecot hits the user's email
> it most likely will have to re-index all new email.

There's no "reindexing". It just sees a new mail and adds it to the
index. Not a problem in any way.
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