Terrible RAID 0 disk transfer rate

[mconway]

I was unraring a 4.5 GB torrent earlier this evening and it took 12 minutes to complete. wtf I thought? On my old machine (P4P800D, P4 3.0C, 2X7k250 RAID 0) the same file was much, much, much faster. I decided to give Winbench 99 a whirl and ended up with the following results:

 

Transfer Rate Begin: 39.7 MB/s

Transfer Rate End: 32.2 MB/s

 

Something is obviously amiss. This was a fresh install using the RAID disk supplied with the motherboard. Stripe size was left at optimum. A 16k stripe would probably be better but that would not explain the slow rates. I never had a chance to fully test my single 200GB Maxtor, but the start transfer rate was on the order of 60 MB/s which is in the ballpark. Any ideas/suggestions as to what the problem with my array might be? System details in signature.

 

Edit. I just swapped SATA cables with no difference. Next I moved my array from SATA 1/2 to SATA 3/4 with the same crappy transfer rate. Just now I rebuilt my array with a 16k stripe and used Acronis to recover my drive. Starting transfer rates still in the 30's. I suppose next up is to try the array on the Silicon Image controller though I'd rather not.

[mconway]

Think I may have solved my problem. I started poking around in device manager under the nForce4 ADMA controller options. There are four options: Let BIOS select transfer mode, Enable read caching, Enable write caching and Enable command queuing. I disabled all 4 and rebooted, not hoping for much. I fired up Winbench and to my surprise my array started out at about 120 Mb/s transfer rate. I then started re-enabling options til I ran into problems. The culprit was enable read caching. With that option enabled my transfer rate plummetted. I just ran HD Tach with only read caching disabled and got the following results:

 

Burst Speed: 1567.7 MB/s :eek2:

Random access time: 16.6 ms

CPU Utilization: 4%

Average Read: 95.3 MB/s

 

So I'm a happy camper again. What's with the insane burst speed anyway

[red930]

Any idea how that got changed? Seems odd that an option would simply turn its self on like that.

 

Glad you found the problem and was able to fix it but man that's weird.

[smiffy]

Just found the same thing sort of

On reading Mconways post disabled read caching

Previous HD Tach

Red bar 200mbs.8.1ms randon access 7% cpu utilisation and average read 95mbs

Disabling read caching

Red bar 237mbs 7.9ms random access 2% cpu utilisation and average read 117mbs

Gonna experimemt more

Smiffy

[Ambian]

Just ran HDtach and got 93MB/s, with 200MB/s Burst...which i wasnt unhappy with. So i went into Device Manager, unticked the Read Caching and now get:

107.2MB/s Transfer Rate

244MB/s Burst Rate

 

:nod: Interesting Stuff.

[soundx98]

Don't believe those HDTach bursts with a RAID 0 array.

 

mconway do you have Cool N Quiet enabled?

[PÿRÓ]

Burst doesnt mean i thing really ...read and write speeds are what you look at

and in raid 0 yes your read speeds are great but your write speeds ???

 

in other words if i have a harddrive that had a read and write speed of say 60 for read and 60 for write then after you raid 0 them you will have (about) 120 read and 30 write ..yes you will get better read speed at the sacrifice of write speed

[mconway]

soundx98, nope have CNQ disabled in the BIOS.

[tompson]

ok, so I'm getting HORRIBLE scores. I'm getting 43MB/s with bursts of 120MB/S. I'm running two WD raptors 74G a raid 0 array.

 

I'm overclocking and my settings are: 10 x 264, 3x HTT multi., 1T, 1:1 ram, 2,2,2,6, and pci-e at stock.

 

Why am I getting such low scores??? Please help.

 

Thanks

[tompson]

ohh and I tried turning off the read cacheing in the device manager but it makes no difference. It's wierd though, there are two instances of the same controller. Is this what you guys have?

[Cascadesss]

Wow... What a difference... with Read caching on, I was getting an average of 95MB/sec. With it off, the average now is 122MB/sec.

 

This was using HD Tach on two 74GB Raptors.

[RyderOCZ]

I find the same thing....

 

however.....Think about what read caching means.....if data is requested from the disk (read), if the data is cached in the buffer or in system memory and the same data is requested before the cache is cleared....the machine does not have to access the drive again, just the buffer or ram which is far faster than accessing the drive.

 

Your drive performance score might go up.....but overal system performance may be lowered because the drive MUST access the drive each time it wants data.

 

My .02 cents.