[Dovecot] So, what about clustering and load balancing?

Timo Sirainen tss at iki.fi
Mon Feb 15 10:02:09 EET 2010

On 15.2.2010, at 8.13, Stan Hoeppner wrote:

> Timo Sirainen put forth on 2/14/2010 1:31 PM:
>> On Sun, 2010-02-14 at 01:16 -0600, Stan Hoeppner wrote:
>>> If you use maildir format mailboxen, you physically can't run into a write lock
>>> contention between the MTA and the imap process because the MTA writes every new
>>> email to a new file name.
>> You're ignoring dovecot-uidlist and index files.
> Apparently I'm missing something.  If the MTA is creating files per Maildir
> specs,

If the mails are delivered by MTA or something else than Dovecot delivery agent, then there shouldn't be any locking contention. But normally using Dovecot deliver should give better performance, and that (reads and) writes dovecot-uidlist and dovecot.index* files, which IMAP/POP3 also reads/writes.

Also I guess it depends on internals, but I'd think creating new files requires some kind of locking/synchronization for the directory, which is similar to locking contention (it can't respond success to file creation until it's verified that another server hadn't already created it).

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