Re: advice on raid controller

RIchard,

> Hi, i'm on the verge of buying a "MegaRAID SCSI 320-2" raid controller.
> I need it to build a db server using 4x ultra320 scsi disks
> i'm thinking raid 1+0 but will try with raid5 too and compare

Depends on your type of database.  If you're doing web or OLAP (lots of
read-only queries) RAID 5 will probably be better.   If you're doing OLTP
(lots of read-write) RAID 10 will almost certainly be better.  But if you
have time, testing is always best.

> as seen:
> http://uk.azzurri.com/product/product.cgi?productId=188

I haven'te used it personally, but what I don't see in the docs is a
battery-backed cache.   Without battery backup on the write cache, IMHO you
are better off with Linux of BSD software RAID, since you'll have to turn off
the card's write cache, lest your database get corrupted on power-out.

--
Josh Berkus
Aglio Database Solutions
San Francisco