RAID Performance/UDMA Modes

[ianbergman]

Hey all,

I have a 4-way RAID stripe with 2 5400rpm drives and 2 7200rpm drives, each 40GB. Granted that it shouldn't be as fast as an array with all 7200 RPM drives, but the performance is abysmal - most benchmarks place it at slightly slower than an old-school 4200 RPMer.

AGH!

The only possible problem I can think of is that one of the drives is in UDMA-Mode 4 and the rest are all in Mode 5. Does this matter and should it be a setting I can change somewhere? The RAID card i'm using is a Promise Fasttrack 100, and i've got a 128k stripe size.

Help! I'm tempted to just give up on the RAID and go buy a single 160gigger whenever I can afford one.

EDIT--blablablablabla
EDIT AGAIN--sigh, Maxtor is monkeyish and their online documentation contradicts itself, but it appears that the drive does not support 5, so it's running in 4 and all the others in 5. I don't know enough about timing issues to know if this is causing the problem?

 

[Frosty3799]

hmm.. i would set up 2 separate arrays, one with the 2 7200 rpm hdds, and then a secondary raid setup with the 5400 rpm-ers. that way the separate arrays contain identical speeds, so it doesnt differe across the one array.

you should be able to switch the "drive in question" to UDMA 5 right in bios.

my 2 cents

 

[ianbergman]

sorry, drive in question is Maxtor 94098U8, if that helps - i was too lazy to look that up before. the prob. with using the bios to switch the drive is that since they're on a separate controller card, they don't appear in the bios, and the FastTrack BIOS doesn't appear to have any settings for such things. Sigh.

Mebbe I will just set up 2 arrays...

 

[Frosty3799]

yea, try the 2 arrays.. and see if that solves it.... hmm i dunno if this would work, ive never tryed before, but maybe you could hook up the hdd in question to your mobo on regular ide slot and switch to udma 5, i dunno if it would remember or anything, but worth a shot i guess??

Josh