FreeBSD 6.0 as storage server with raid5?

[Oliver Fromme]

Sorry for the late reply ...

Torfinn Ingolfsen <torfinn.ingolfsen at broadpark.no> wrote:
 > Highpoint RocketRAID 1640    (4 ports)
 > Promise FastTrak S150 SX4    (4 ports)
 > Promise FastTrak S150 SX4-M    (4 ports)
 > Highpoint RocketRAID 1810A    (4 ports)
 > Highpoint RocketRAID 1820A    (8 ports)
 > Intel RAID Controller SRCS16    (6 ports)
 > [...]
 > 1) can I install several 4-port RAID controllers in one machine?

Yes.
There's no reason why you shouldn't be able to do that.

 > I can get two RocketRAID 1640's for the price of one RocketRAID 1820A.

Note that the HPT 18x0A have an onboard processor which
does the XOR (parity) calculations for RAID-5.  For the
non-A versions, the host CPU has to do those calculations
(in the driver), which can be quite a noticable burden.

 > 3) disks - I understand the importance of using disks from different
 >    production runs. Some people have suggested to use disks of different
 >    brands as well, but there were no conclusions. Should I stick to the
 >    same brand and model, or can I use disks of different brands as long
 >    as they are of the same size?

Well, both strategies have advantages and disadvantages.
But given the fact that the "big" commercial appliance
companies (such as NetApp) ship their filers with disks
of the same brand, I guess it's not terrible mistake to
do so.

 > 4) PSU considerations. How big a PSU do I need if I want to run two
 > controllers and eight disks in one machine? are there any rules of thumb
 > for sizing this?

There are usually three numbers of power-usage provided
for hard disks:  power usage when idle, max power usage
when busy during normal operation, and max poer usage
during spin-up.  The latter is the largest number, of
course.  If your disks all spin up at the same time, then
you PSU have to be able to provide enough power for the
sum of all of your disks (plus the rest of the system),
which can be quite a lot.

Some controllers have a setting to enable staged starting
of the drives, i.e. one after the other.  This can reduce
the maximum PSU requirement considerably if you have a
lot of disks.

Best regards
   Oliver

PS:  I assume you already know this, but I'd like to note
this for all readers:  RAID (of any kind) does not replace
reliable backups.  Always make proper backups, independent
of your RAID (if any).

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

(On the statement print "42 monkeys" + "1 snake":)  By the way,
both perl and Python get this wrong.  Perl gives 43 and Python
gives "42 monkeys1 snake", when the answer is clearly "41 monkeys
and 1 fat snake".        -- Jim Fulton