Not getting 300 MB/sec

[derrickc]

Hello,
I just bought a Burly 5 enclosure and FASTA-4e 4 port PCIe SATAII Host Adapter from MacGurus. I put in 2 1TB Seagate Barracuda 7200.11 drives.

I've removed the jumpers that limit the drives to 150MB/sec.
They are setup as RAID 0 using Mac Disk utility.
I'm using Xbench to test. Here are the results of a couple tests...
sequential write/read
write 123.95 MB/sec 132.24 MB/sec
write 176.73 MB/sec 172.69 MB/sec
read 20.09 MB/sec 18.90 MB/sec
read 188.95 MB/sec 176.48 MB/sec

As you can see, I'm not getting near the 300 MB/sec speed. This is faster since they are RAID 0. Shouldn't I be able to get faster speeds than this? When they were single drives I was getting around 90 MB/sec average from them.

Also, to be clear, I couldn't get Raid Shield to work. It seems like it will only work with CalDigit's external cases. Am I correct in this assumption or is something not setup properly?

Thanks!
Derrick

[rwm]

I am not the RAID specialist. I think you can generally with proper drives and setup if using 2 drives double that. So if you were getting around 90 MB/sec with a single drive your numbers don't seem to far out of line.

Rick has tested the 7200.11 in a variety of setups and will be of much better help to tweak or speed things up. Many people use Quickbench as a tool to measure speed using the extended 20 - 100 MB files. If you have QB try it and see your numbers. I believe it is a shareware application.

What is on the drives? Partitioned? Other drives in the computer and how it is setup? Where are your Apps, System, Users etc.

[derrickc]

The drives have nothing on them.

[Damien]

No drive runs better than about 90MB and if you have 2 you would be at about 180MB a sec which you are. Also even if you had enough drives to reach 300 you wouldn't get it... you could get close but controller overhead would keep you from reaching the full 300

[derrickc]

thanks for the info. If that's the case, why do they call them 300MB/sec drives?
Thanks
D

[ricks]

thanks for the info. If that's the case, why do they call them 300MB/sec drives?
Thanks
D

Really they don't call the drives 300 MB/sec. They do call the bus specification as 300 MB/sec. It is meaningless marketing bullshit to call any SATA drive 300 MB/sec since the only way to get over 100 MB/sec is in a RAID.

Removing the SATAI jumper DOES NOT MAKE THE DRIVE FASTER. In fact, that jumper has absolutely nothing to do with speed at all. It only turns SSC (Spread Spectrum Clocking) on and off. SSC is a server feature that can break some SATA controllers.

Even if you turned a drive to SATAI it would not effect the speed since no drive is over 100 MB/sec a SATAI bus at 150 MB/sec doesn't make for any kind of a limitation on performance.

Sounds like you are getting what you are supposed to get with those Seagate drives. Here's the results I got with them: Seagate 7200.11 Thread (http://www.macgurus.com/forums/showthread.php?t=24148).


Rick

[derrickc]

Excellent. Thanks for the education. I'm loving having this setup already. I'm going to raid0 my internal drives too! I've had so many problems with external firewire drives (6 drives die, one of them 4 times) that I decided to get something better (and faster). I feel so much less stress already not that I have the Burly 5 bay to expand!

Thanks for everything
D