[Dovecot] Hardware infrastructure for email system

Alex Crow acrow at integrafin.co.uk
Sat Jun 23 21:10:37 EEST 2012

On 23/06/12 18:09, Andrzej A. Filip wrote:
> On 06/23/2012 01:23 PM, Reindl Harald wrote:
>> Am 23.06.2012 13:09, schrieb Wojciech Puchar:
>>> Finally i would recommend to get rid of RAID6. It's terribly slow on writes and
>>> writes are common on mail server.
>> depends, it is slower than RAID5, but safer
>>> Buy cheapest but largest SATA drive and use RAID1 (or RAID1+0) setup.
>> oh no please do not recommend SATA crap with RAID1 and think
>> it is faster than RAID6 - the additional writes doe snot mat
>> if the whole disk-system is much faster and RAID1 has no benefit
>> in performance
>> nobody will use SATA disks for high peformance servers in
>> production - really nobody these days!
> Could you specify/define your idea of "high performance servers" land
> border?
> It may reduce the flame war.


With dovecot, you can separate indexes and email, and with dbox/mdbox, 
have ALT storage, so for instance you could keep your indexes in a 
RAID10 of SSDs, recent email on a RAID10 of 10kRPM/15kRPM SAS drives, 
and older email can go on a load of 5k/7.2k SATA drives in RAID6, or on 
a NAS via NFS.

Note: with *dbox your indexes are the only place your mail flags are 
kept, so don't risk a single drive or even RAID5 for your index store.

This is what I am moving into production from dovecot 1.x on a single 
RAID6 array (hardware, LSI controller, 6 10k SAS drives in RAID10) which 
has served very well for a while but is not getting too small for all 
our mail. Performance has been good for up to 350 users, average mailbox 
size >4G, about 25-35k incoming mails per day.



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