How fast is RAID 0 with 4 HDD?

[chainbolt]

I just set up a RAID 0 array on my Promise Fasttrak 100 with 4 identical HDD (128k block size)

My question:

The Fasttrack 100 manual explains that "a RAID 0 array with 2 drives will transfer at about twice the speed of the slowest HDD in the array. A RAID 0 array consisting of 4 HDD will transfer about 3 times the speed of the slowest HDD in the array".

In another forum somebody stated that a 4 HDD set-up on 2 channels cannot be faster than a 2 HDD set-up on 2 channels. Somebody else said this is not true, because a channel is not 100% hogged by 1 disk all the time, so even when using the same channels, 4 HDD are still faster than 2 HDD on 2 channels.

What is true? I get better scores with 4 HDD on 2 channels, than with 2 HDD on 2 channels, but just 10% and that might be within the margin of error. Or not?

 

[bigshooter]

use 2 different raid 0 volumes. The performance benefits should start to drop off, plus it will take more processor load to calculate teh striping the more disks you have. Plus, I hope you know that if one drive goes bad, becomes corrupted, whatever, you have lost all your data on the entire volume.

 

[joburnet]

Anandtech did a very good article about this not too long ago, you should check it out. I think with 4 drives they got up to 80MB/sec or more, don't remember exactly though.

 

[dowxp]

u need a big cpu for that. it will jack at least 25% cpu.

 

[chainbolt]

<< Anandtech did a very good article about this not too long ago, you should check it out. I think with 4 drives they got up to 80MB/sec or more, don't remember exactly though. >>




If you are talking about the Anand RAID article from 18 June, I know this one, but they used only 2 HDD (not 4 HDD) for their benchmarking, as far as I remember. If you have another report in mind, please let me know, it would be interesting to see scores with 4 HDD on 2 channels.

 

[chainbolt]

<< u need a big cpu for that. it will jack at least 25% cpu. >>



thanx, it's not a problem, I'm running a TB 1.33@1.6 on a 7DXR mobo, that's good enough, I think.
My question is: is there any speed advantage in RAID 0 with 4 HDD versus 2 HDD?

 

[Ahz]

Tom's had a RAID review a while back comparing 1->4 drives.

Tom's RAID Article

It was based on an ATA66 RAID controller, so the results should scale a bit more for ATA100.

 

[chainbolt]

<< Tom's had a RAID review a while back comparing 1->4 drives.

Tom's RAID Article

It was based on an ATA66 RAID controller, so the results should scale a bit more for ATA100. >>




thanx a lot, that was exactly what I was looking for! it shows that RAID 0 with 4 HDD is indeed faster than RAID 0 with only 2, with some limitations of course, great!