dovecot - Oct 2011 - lmtp performance

Hello:

In the process of migration from version 1.2 to 2.0 have tried to use 
lmtp instead of lda as delivery agent.

But unfortunately througput we get is poor with lmtp compared to lda.
In peak times with lda we are able to deliver over 1800 messages/minute 
(high I/O but not affecting service) but if we switch to lmtp cannot 
deliver more than 300 mess/minute (very low I/O).

This is enough for normal work but low under heavy load (distribution 
lists messages sometimes stay queued for 4 hours before deliver).

We have arround 50000 boxes and use postfix as MTA

How to increase lmtp performance?


dovecot config for lda and lmtp:

protocol lda {
   auth_socket_path = /usr/local/var/run/dovecot/auth-master
   info_log_path = /var/log/mail/dovecot_deliver.log
   log_path = /var/log/mail/dovecot_deliver.log
   mail_plugins = quota sieve zlib
   postmaster_address = postmaster at upm.es
   sendmail_path = /usr/lib/sendmail
}

protocol lmtp {
   info_log_path = /var/log/mail/dovecot_deliver.log
   log_path = /var/log/mail/dovecot_deliver.log
   mail_plugins = quota sieve zlib
   postmaster_address = postmaster at upm.es
   sendmail_path = /usr/lib/sendmail
}

In postfix I have:

mailbox_transport = lmtp:unix:private/dovecot-lmtp



Thanks in advance.

-- 

------------------------------------------------------
Juan Carlos Sanchez Hernandez
Universidad Politecnica de Madrid
------------------------------------------------------

A particular reply (not to the list) has told me to try:

"
Add to service lmtp:
process_min_avail = 20
"

And yes, it works (unless for me), so I want to share it with everybody.

Have not exactly measured performance but this morning have seen over 
1400 messages/minute with lmtp under heavy load.


What the "process_min_avail = 20" in service lmtp (or anywhere else) 
exactly imply? cannot find a reference in wiki2 . I suppose it means 
than 20 lmtp processes are always open waiting for new connections and 
so reducing startup latency, isn't it?

Thank you.
>
> On Mon, Oct 17, 2011 at 6:06 AM, Juan Carlos Sanchez 
> <juancarlos.sanchez at upm.es <mailto:juancarlos.sanchez at
upm.es>> wrote:
>
>     Hello:
>
>     In the process of migration from version 1.2 to 2.0 have tried to
>     use lmtp instead of lda as delivery agent.
>
>     But unfortunately througput we get is poor with lmtp compared to lda.
>     In peak times with lda we are able to deliver over 1800
>     messages/minute (high I/O but not affecting service) but if we
>     switch to lmtp cannot deliver more than 300 mess/minute (very low
>     I/O).
>
>     This is enough for normal work but low under heavy load
>     (distribution lists messages sometimes stay queued for 4 hours
>     before deliver).
>
>     We have arround 50000 boxes and use postfix as MTA
>
>     How to increase lmtp performance?
>
>
>     dovecot config for lda and lmtp:
>
>     protocol lda {
>      auth_socket_path = /usr/local/var/run/dovecot/auth-master
>      info_log_path = /var/log/mail/dovecot_deliver.log
>      log_path = /var/log/mail/dovecot_deliver.log
>      mail_plugins = quota sieve zlib
>      postmaster_address = postmaster at upm.es <mailto:postmaster at
upm.es>
>      sendmail_path = /usr/lib/sendmail
>     }
>
>     protocol lmtp {
>      info_log_path = /var/log/mail/dovecot_deliver.log
>      log_path = /var/log/mail/dovecot_deliver.log
>      mail_plugins = quota sieve zlib
>      postmaster_address = postmaster at upm.es <mailto:postmaster at
upm.es>
>      sendmail_path = /usr/lib/sendmail
>     }
>
>     In postfix I have:
>
>     mailbox_transport = lmtp:unix:private/dovecot-lmtp
>
>
>
>     Thanks in advance.
>
>     -- 
>
>     ------------------------------------------------------
>     Juan Carlos Sanchez Hernandez
>     Universidad Politecnica de Madrid
>     ------------------------------------------------------
>
>
>
-- 

------------------------------------------------------
Juan Carlos Sanchez Hernandez
Universidad Politecnica de Madrid
------------------------------------------------------