dovecot, maildir, UFS 2 performance

[Laszlo Nagy]

>
>> #1 maildir stores each message in a separate file. I think I need to 
>> dedicate a separate disk slice for maildirs and decrease block size 
>> on it. How big should the blocksize be?
>
> i have everything (/) on single partition on most of my servers, 
> including those having lots of mail.
I don't think that is clever. sysinstall creates different partitions 
for / /usr /var and /tmp by default. There must be good reasons for this.
>> #2 searching in messages is a common operation. Possibly read speed 
>> is very most important. But since there will be thousands of files to 
>> open, seek operation is also important. On which RAID array should I 
>> put mail dirs?
>
> dovecot do make indexes and scans all files only when rebuilding them.
Except when my users search for a text in the "message body". 
Unfortunately, they often do this. :-(
> assuming you configured your RAID1+0 properly it will give you MUCH 
> more performance from 10 disks, than RAID1 on 2 - a bit faster - drives.
>
> IMHO you wasted money for SAS drives, simply having SATA only system 
> could be enough.
This is true for raw read/write speed. But some I/O operations are seek 
intensive. Seek time for a 15 000 rpm SAS disk is lower than it is for a 
10 disk SATA2 RAID. Seek intensive operations should go to SAS. But I'm 
not sure what they are. If you say that dovecot is not seek intensive 
then you answered my question. :-)

> just keep your SAS drives for OS, ports, sources, logs, whatever, 
> while /home on your big RAID1+0 volume.

Thank you

Laszlo