RAID configuration question

[Gurm]

Ok folks,

As some of you know, for a while now I've been running IDE-100 RAID. Well, I found out a few things about the baby RAID chipset on my motherboard (which I upgraded to full RAID via a resistor and some bios tampering):

1. It doesn't handle multiple arrays to save its life (CPU usage jumps from 2% to 35% - OUCH!), and...

2. It causes problems if I'm trying to use it and the VIA (onboard 686B) and the SCSI all at once for hard drives (boot device contention like you wouldn't believe).

So, I'm thinking of rearranging things. The way I've been running it is with two IBM 75GXP's (which are nowhere NEAR as silent as everyone thinks - their spindle speeds are off by just enough to make a harmonic squeal that drives me nuts) raided up at 16KB to make a 90GB array.

I also have a third drive (actually a third and fourth, but the fourth one is a mismatched drive) which I've been using to stream CD's to and from, running from the VIA controller.

Here's my question:

Would the speed gain from adding the third drive to the main array offset the concurrency problems from streaming CD's to and from the system drive (which would then need to be defragmented daily)?

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[xortam]

In my case, I found the two drive array worked slightly better for me than a three drive array. Adding additional drives may cause excessive resource usage (CPU processing, memory, bus bandwidth) accessing data that exceeds your I/O request. You need to look at how you use your system so that you can profile your I/O and configure your array accordingly. Don't get blinded by raw throughput numbers. I highly recommend the ZD WinBench benchmarks for tuning because they playback actual application I/O so you can see how your system does under real world conditions.

[Gurm]

Thanks for the quick reply Xortam - I sort of suspected as much. What do you use for a stripe size?

Of course having RAID5 would be nice - I have my eye on the new Promise Supertrak-100 for that for my NEXT machine.

- Gurm

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Listen up, you primitive screwheads! See this? This is my BOOMSTICK! Etc. etc.

[xortam]

I never cared about other than RAID 0 for my home machine. I don't need 24x7x365 uptime so I spend the time and money on backups rather than redundant disk drives and go for maximum performance. AFA configuration ... I set my RAID 0 stripe size to 64 KB on my two drive array. Second best setup was the 64 KB stripe on three drives. Don't use my setup as a guide since your HW, SW, and configurations will be quite different. Also, you need to evaluate what type of applications are important to you as that can greatly determine which way you want to set things up. WinBench is great because, along with overall ratings via the Business Disk WinMark, High-End Disk WinMark, CPUmark, and FPU WinMark, it will also break it down by specific business and high-end app metrics.