dovecot - Jan 2007 - Large & busy site, NFS with deliver only servers

Timo / Others,
 
I have been working on a new installation for a fairly busy site, and after
many weeks of tribulation have come to an architecture Im happy with:
2x Debian (2.6.18) - MXing machines running Postfix / MailScanner /
Dovecot-LDA (A slightly patched RC17 for prettier Quota bounces)
2x Debian (2.6.18) - Mail retrieval machines running Dovecot IMAP/POP3
(Currently RC17)
3x Node Isilon NFS cluster (NetApp type devices)
 
I chose Dovecot-LDA over Postfix-Virtual / Maildrop / Procmail due to its
hassle free auto creation of new user maildirs, and the funkyness of built
in Sieve functionality.  The on the fly indexing sounded like a bonus at the
time.  However as Im sure all people who stress test with index's stored
over NFS find, index locking makes for some 'spectacular crashes' (see
others previous posts).  
I have tried out the recommended mount options and locking methods to no
avail.  Once under some stress, say ~60 messages a minute from the two front
end machines, understandably the index's get pickled instantly.  So as a
hack way around the index locking problems, I have configured the MXing
machines to index locally to no where (/tmp) - and deal with the very
slightly slower IMAP/POP3 performance on the retrieval side.  
 
Is there way to tell/patch Dovecot-LDA not to bother with indexing? So Im
not creating unused index files.
 

Cheers
__________________________________________
Dean Manners

On Mon, 2007-01-22 at 22:08 +1100, Dean Manners wrote:
> Is there way to tell/patch Dovecot-LDA not to bother with indexing? So Im
> not creating unused index files.
mail_location = ...:INDEX=MEMORY

If you want the same dovecot.conf to use indexes for pop3/imap, put the
mail_location inside protocol lda {}

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Timo/others,
		Further to my index problems with dovecot-lda over NFS when
busy.  Is it possible to also stop the writing of dovecot-uidlist?  I have
tried a shot in the dark with :INDEX=MEMORY:UIDLIST=MEMORY but it doesn't
seem to stop the writing of the dovecot-uidlist upon delivery.  Which when
busy, causes deliver processes to hang (and usually timeout/defer to the
mta) with many log entries such as:

Feb  5 13:15:07 mailfilter01 deliver(stresstest at stresstest.com):
rename(/var/mailstore/stresstest.com/1/stresstest at stresstest.com/.Postal/dov
ecot-uidlist.lock,
/var/mailstore/stresstest.com/1/stresstest at stresstest.com/.Postal/dovecot-ui
dlist) failed: No such file or directory

I know taking out the uidlist and indexing takes away the key benefits of
deliver. However the only way I can see being able to deliver concurrently
to NFS mailstore is by blindly dropping in the messages ?


Thanks
__________________________________________ 
Dean Manners
 
> -----Original Message-----
> From: dovecot-bounces at dovecot.org 
> [mailto:dovecot-bounces at dovecot.org] On Behalf Of Timo Sirainen
> Sent: Monday, January 22, 2007 10:38 PM
> To: Dean Manners
> Cc: dovecot at dovecot.org
> Subject: Re: [Dovecot] Large & busy site, NFS with deliver 
> only servers
> 
> On Mon, 2007-01-22 at 22:08 +1100, Dean Manners wrote:
> > Is there way to tell/patch Dovecot-LDA not to bother with 
> indexing? So 
> > Im not creating unused index files.
> 
> mail_location = ...:INDEX=MEMORY
> 
> If you want the same dovecot.conf to use indexes for 
> pop3/imap, put the mail_location inside protocol lda {}
> 
>