RAID access time

[lifechooser]

Hi 2 all

I have recently built a RAID0 array, anyhow, my disc access time is between 16 and (very often) 20 ms. My discs are DiamondMax 10 & 20, and actually the access time should be <9 msec (access time of each of the discs in single mode). Stripe is 64k, cluster size is win default 4k, controller is onboard SiS 180, OS is win xp sp2. What have i done wrong? Should I take lower stripe (and how does it improve the access time), or is it something else? Bios & drivers are the last available.

Thx

 

[xvi]

Hi 2 all

I have recently built a RAID0 array, anyhow, my disc access time is between 16 and (very often) 20 ms. My discs are DiamondMax 10 & 20, and actually the access time should be <9 msec (access time of each of the discs in single mode). Stripe is 64k, cluster size is win default 4k, controller is onboard SiS 180, OS is win xp sp2. What have i done wrong? Should I take lower stripe (and how does it improve the access time), or is it something else? Bios & drivers are the last available.

Thx

It would work a little better to have the disks a little more matched. I'd ditch the DiamondMax 20 and find another DiamondMax 10. It looks like the 20 has a 11ms Average Seek Time, compared to the 10's 9ms. Also, the 20 only has a 2MB cache where the 10 has 8MB to 16MB.

My drives have a 8-9ms seek time, but in RAID 0, they're more like 16ms.

Edit: Or better yet, pick up a Perpendicular Recording drive. They're great performers and they're quite cheap. I have a pair of Seagate Barracuda 7200.10 250GB drives in RAID 0. You can buy them at newegg.com for about $75 USD. HDTach reports that they can do 160MB/s peak with about 140MB/s average. That's about the same speed as a pair of WD 74GB Raptors in RAID 0 for half the price. The Raptors will have better seek times, but that's about all they offer (besides also being noisy).

 

[lifechooser]

Thx 4 reply

Is the "unmatching" of discs the reason that i can't successfully set stripe size of 16k? I can install win xp on it but as soon as I start everest for instance, I get BSOD IRQ_DRIVER_NOT_EQUAL_OR_LESS and as cause is mentioned the scsiport.sys? Currently the stripe is set on 32k and seek time dropped to 15-16 ms

Thx

(Sorry for my bad english)

 

[xvi]

Thx 4 reply

Is the "unmatching" of discs the reason that i can't successfully set stripe size of 16k? I can install win xp on it but as soon as I start everest for instance, I get BSOD IRQ_DRIVER_NOT_EQUAL_OR_LESS and as cause is mentioned the scsiport.sys? Currently the stripe is set on 32k and seek time dropped to 15-16 ms

Hmm.. I'm not completely sure what affect your RAID stripe size has on actual performance. I'd imagine that it's similar to cluster size performance. I've heard that larger is better, but I always thought it'd be the other way around. Just go with the default sizes.

 

[lifechooser]

Well, the "optimal" stripe size is elaborated often enough and my personal opinion is that there isn't such thing, anyhow my controller offers 16 - 256 k sizes, and probably it can't handle "extremes" (haven't tried 256k yet) And of course, there is the disks issue, they aren't same. As I'm not such a freak who aims for 1-2 ms (is it noticeable in real life at all???) or 5-10 mb/s transfer....I'm happy with speed my 32 stripe gives me even with different disks. I do not video rendering, I'm not running databases, RAID became an option for me cause I wanted to upgrade HDD anyhow, so I came to RAID and then looked for similar HDD to buy. In deed, win xp loads better, games levels load faster, ms office apps open faster....and with stripe size of 32k system doesn't crash.

I was just wondering (eternal curiosity) why the BSOD comes - above is just a simplified idea

Anyhow, thx for reply again