[Dovecot] Dovecot and SSD

[Bryan Vyhmeister]

On Thu, Jul 29, 2010 at 9:57 PM, Chris Hoogendyk
<hoogendyk at bio.umass.edu> wrote:
>
> Curtis Maloney wrote:
>>
>> Umm... apart from "shiney toys", is there any legitemate reason for such
>> expense on performance tuning?
>>
>> I ask because we have about 30 users using our IMAP server (Dovecot 1.1),
>> which also serves as our main Samba server, and until recently was also a
>> CUPS server.
>>
>> This on a Sun V100 ( 450MHz UltraSPARC-IIi ) with 1G RAM and two dull,
>> standard IDE HDDs ( a 40GB for OS and mail, and a 320GB for Samba).
>
> I was going to bring up something like that, but I wasn't sure it was fair
> comparing my server.
>
> I do not have SSD's. But, I have a larger user base and I have a Sun T5220,
> which is 8 core, 8 threads per core, etc. The drives are 15Krpm SAS. Using
> Sendmail, mimedefang, Dovecot, Squirrelmail, etc. Also running Apache2 with
> Drupal, MySQL, gene sequencing apps, PostgreSQL, Samba for file sharing and
> printer spooling, as well as some other stuff. Squirrelmail/Dovecot is
> virtually instantaneous even with very large mbox format inboxes.
> Thunderbird mail checks via Dovecot are also virtually instantaneous. I have
> over 1500 accounts on the system, although probably only a few hundred are
> very active. Granted, it is summer, and things will pick up in the Fall, but
> I doubt it will push this server too much.

I do understand where both of you are coming from completely. I have
also run a similar setup as the Sun Fire V100 with a Sun Fire V120 and
it performed beautifully. There are two main scenarios where using an
SSD is interesting to me. Both scenarios involve using a Mac mini. In
one case it would be a 1.5 GHz Mac mini G4 with a 16 GB SLC Transcend
SSD. Another would be what I was referring to earlier with an Intel
Mac mini 2.0 GHz Core 2 Duo. In either scenario, I don't like being
stuck with only a single hard drive. I feel more confident that an SSD
is less likely to fail in this type of environment. As a benefit, its
performance also makes up for other performance issues with the given
hardware. Maybe these are bad scenarios and examples but they seem to
be potentially good use cases for an SSD. Certainly using an SSD,
particularly an IDE one with a Mac mini G4 is size limiting which
makes this impractical for anything but a very small setup or even
personal installation.

If I were building a more powerful server setup, I would absolutely
use a ZFS mirror or raidz1/raidz2 with SSD L2ARC and/or ZIL or
potentially hardware RAID with two or more hard drives. While this
would be a better design in every way it is also substantially more
expensive. Thanks for your comments and I do understand that all of
this may be somewhat silly. I will be implementing something with SSD
if only for the fun of it.

Bryan