[Dovecot] mail open slowly

[Bernics Gábor | Penta Unió Zrt.]

Thanks a lot to everybody 

First step I will upgrade to dovecot2.


I will write my experiences. 

"Running with fsync disabled is like
having sex with a Bangkok prostitute without a condom while juggling
chainsaws while driving drunk at 250kph at night without headlights."


:-) 

Gabor 

2012-10-27 20:27 időpontban Stan Hoeppner ezt írta: 

>
On 10/27/2012 6:58 AM, Bernics Gábor | Penta Unió Zrt. wrote:
> 
>> I
use dovecot LDA (+sieve) with maildir. conf:
http://pastebin.com/9fhYD58g [1]
> 
> Next time simply paste "dovecot
-n" output into your email.
> 
> Assuming Dovecot is the only program
accessing the maildirs, try:
> 
> maildir_very_dirty_syncs=yes
> 
> That
may help some.
> 
> It may not have been a factor in this case, but note
that when anyone is
> doing a full text search on a large mailbox on
this hardware with
> maildir you will see latency, and it is
unavoidable. Neither a single
> 7.2K SATA spindle nor md/RAID1 pair of
them, has enough seek capacity to
> service all the sector requests in a
timely fashion.
> 
> Also, I noticed you disabled fsync. This is a very
very bad idea for a
> mail server. If you lose power, or suffer a
kernel/hardware/etc crash,
> you lose the Linux buffer cache contents.
Thus, you may lose emails
> that haven't been flushed to disk, and
possibly get index file
> corruption if mmap'd pages haven't been
flushed.
> 
> Running with fsync disabled is like having sex with a
Bangkok prostitute
> without a condom while juggling chainsaws while
driving drunk at 250kph
> at night without headlights.
> 
> fsync does
hurt write performance to a degree, especially with maildir
> storage,
but will likely be invisible on a small server with few
> users/light
load. And it will prevent potentially severe problems with
> file
corruption and/or lost emails.

 

Links:
------
[1]
http://pastebin.com/9fhYD58g