Best choice of disk array for (informix) database server

[Ben Mumford]

Background:

Currently run a K420, 2x disk array model 20 (40*4.2GB as RAID5). Machine is Informix database server, up to 300 concurrent users, 200 with write access. Looking to upgrade machine, possibly to L2000/3000, will also upgrade RAID. Considering straying from RAID 5 since we would like to maximise write performance (and we have require relatively low capacity - say we wish to double effective capacity to 250GB).

Questions:

(a) Can you force a VA7x00 to RAID 10 (or any other level)?
(b) Those with experience of using VA7x00 and RAID 5DP in a database server, how have you found performance?
(c) Anyone with strong opinions (or experience) of different RAID levels for database servers in an environment where low cost of storage is not a priority?

Many thanks,
Ben

[Enes Dizdarevic · Accepted solution]

a) Yes, you can disable AUTORAID mode and use raid 1/0
b) RAID 5DP has lower performance than RAID5 (5%) but this is more then compensated by the fact that in Autoraid mode at least 10% of disk space is allways in raid 1/0 and is used as "cache" for raid5dp (data read from raid5dp and changed in memory are writen in raid 1/0 first and latter converted in raid5dp if needed). If you set active hot spare (hot spare space is distributed accros all drives) this arrea is also used as raid 1/0 "cache" for raid5dp (until needed for rebuild).
c) because of b) in AUTORAID mode on VA you will get database performance allmost as in raid 1/0. There is no real need to disable autoraid mode and use raid 1/0 only.