Poor benchmark results for a RAID 0 setup??

[KBD]

I decided to run some HDD benchmarks on 2x 320GB Barracudas 7200.11 in RAID 0 on a new systems i built for someone. First off, the strange thing is that HD Tach and HD Tune give totally diffrent burst rates for the RAID 0 setup. Furthermore, the Random Access Times and Burst Rates are just horrible, worse than my single non-RAID 150GB Raptor and Barracuda 320GB 7200.10. Here are the results for 2x RAID 0 drives:

HD Tach

Burst Rate: 436 MB/s
Randon Access Time: 17.4ms
Average Read: 187.8 MB/s

HD Tune

Burst Rate: 89.9 MB/s
Randon Access Time: 16.6ms
Average Read: 178.3 MB/s

As you can see there is some discrepancy between the 2 benchmarks in case of Random Access Times & Avg Read, but the discrepancy between Burst Rates is humongous! 436 MB/s for HD Tach and 89 for HD Tune. I think that HD Tach is way off, 89 looks like it could be closer to the truth, but i it still very low comparing to my single drives, here are their results:


HD Tach

WD Raptor 150

Burst Rate: 133.7 MB/s
Randon Access Time: 8.9ms
Average Read: 75.3 MB/s

Barracuda 320 7200.10

Burst Rate: 134 MB/s
Randon Access Time: 13.7ms
Average Read: 59.7 MB/s

HD Tune

WD Raptor 150

Burst Rate: 116 MB/s
Randon Access Time: 8.2ms
Average Read: 67.8 MB/s

Barracuda 320 7200.10

Burst Rate: 111 MB/s
Randon Access Time: 13.5ms
Average Read: 59 MB/s


So judging by these results my single drives beat the 2 drives in RAID 0 in every test except for Avg Read, how could this be? Are these normal results?

 

[Deleted member 3]

Burst tends to be screwed up, I have a far lower burst than average read. Really makes no sense.
The Raptor is a 10K disk, its sole purpose is to have lower access times.

 

[KBD]

So you are saying these are normal numbers? Is there a way to measure burst rate accurately? And what about access times on the RAID 0 array, are they supposed to increase? As one can gather from the results, the access times on the single 7200.10 Barracuda are lower than on the 2 RAID 0 drives.

 

[Sasqui]

Perhaps a difference in block size between the two programs?

 

[KBD]

Perhaps a difference in block size between the two programs?

Good point Sasqui. i was actually gonna ask about that. In HD Tune the block size defaults to 64kb. I dont think i can change it in HD Tach. But does anyone one know which block size should the drives be tested at? Is it fine to leave it at default 64KB for HD Tune?

 

[twicksisted]

Good point Sasqui. i was actually gonna ask about that. In HD Tune the block size defaults to 64kb. I dont think i can change it in HD Tach. But does anyone one know which block size should the drives be tested at? Is it fine to leave it at default 64KB for HD Tune?

it all depends on what you're going to use the computer for... large file storage, small file storage, database etc.. small stripes with large data is pointless and large stripes with small data etc..

Im using 128k stripe on my raid 0 setup and its pretty decent.

 

[KBD]

yes, i'm using 128k stripe for this RAID 0 array also. I used that only because the Intel RAID setup utility recomended that for this array. I also read an article on the subject beforehand and it seems that there is a lot of debate in regards to stripe sizes for arrays. Anyway, i think i should've tested the RAID array with 128 block size with HD Tune as i can change it in that program, i think i'm gonna retest and see what happens.

 

[Sasqui]

Yea, makes sense. If HD Tune defaults to a larger block size, the results would definitely be lower. If it's larger than your allocation unit size, then the numbers would likely go *way* down - presumably would have to read at least two units ber block!