multiple messages per second to a single mailbox

[Chad M Stewart]

On Aug 17, 2015, at 9:30 AM, Gregory Finch <gfinch at ldmltd.ca> wrote:

<..snip..>

> With that many messages, it may be the index updates that are slowing
> things down. Depending on your needs or how you use this folder (it
> sounds automated to me), you may not need the indexes on disk at all. If
> you set the indexes to RAM, it may help.
> 
> mail_location = maildir:~/Maildir:INDEX=MEMORY
> 
> as per http://wiki2.dovecot.org/MailLocation#Index_files
> 
> If indexes in RAM isn't an option, maybe just put them on a separate
> spindle / SSD would help.
> 
> Please note I'm shooting from the hip with this advice, I don't have a
> system that pushes dovecot that hard.
> 
> Greg
> 
> 

This particular mailbox is unique.  This mailbox holds a copy of member to member communications.  The mailbox also receives a lot of unfiltered spam.   You're right, it is the index updates that were limiting the message insertion rate.  I wrote a sieve script that divides the messages based on the first character of the message-id header.  For now this appears to be enough to spread out the index updates.  The performance metrics indicate I'm now seeing double the IOPS as before the sieve script. With no noticeable increase in IO wait times.

If the sieve script ever stops being enough, then I'll look into moving this mailboxes index files to RAM.

Thank you for the tip!


Regards,
-Chad