Whats wrong with my RAID 0?

[liftedcj7on44s]

Ok i have 2 120gig drives SATA 8MB cache setup in RAID 0. one is a seagate drive and one is a WD drive. This setup doesnt seem to net me any performance gains that i notice, wondows still takes 4 bars to load. these are my HD tach scores
burst speed is 183.7mb/s
random access is 13.1ms
cpu utilization is 2%
average read is 100.5mb/s

now i also have a single WD 250 gig SATA 16mb cache drive and it gets
burst speed is 172.6mb/s
random access is 13.4ms
cpu utilization is 2%
average read is 55.4mb/s
THe only big difference is in the average read times, so why is my raid 0 not so good? should i add the other 250gig drive in with the 2 120's?

 

[liftedcj7on44s]

ok i defragged the drive with perfect disk which was but 0.8% fragmented and got
242.6mb/s burst speed
98.4mb/s average read
13.1ms random access
and 4% cpu usage
are these scores low?

 

[tuskenraider]

Scores seem about right. The higher average read speeds are beneficial moving around and manipulating big files. While you shouldn't expect some amazing transformation in your PC's general speed, you should at least see some decrease in boot times and loading bigger programs. Typically 10-20% reduction, if not, maybe the drives don't work together to well. You'd probably better off with a single WD Raptor than running 2 7200rpm drives in RAID0 if you're looking to speed up things a little bit.

 

[emboss]

THe only big difference is in the average read times, so why is my raid 0 not so good?

The average read speeds should be the only thing that change. The burst speed is independant of actual off-the-platter HDD speed (and performance). The access time for most 7.2K drives is about the same (give or take a ms or two) and if anything is made worse (larger) by RAID0. So seeing approximately the same numbers for you array and single drive is not unusual. The CPU utilization only really has a statistically significant number if you're running software RAID5, so in this case it's not surprising that there's no difference. This leaves the average (sequential) read speed, which increases significantly with the RAID0 array. Which is as expected.

An average RAID0 read speed of 100 MB/sec implies a single hard drive read speed of 50 MB/sec which would sound about right for 120 GB drives.

edit: Fixed up quoting.

 

[liftedcj7on44s]

Thanks for your replies guys, would it be beneficial to add the 250gb drive in with the 2 120's in raid 0?

 

[tuskenraider]

Again, no. All you'll do is increase your maximum transfer rate and you'll probably see an increase in seek times(bad). Most benchmarks, tests, etc. show that running more than 2 drives in RAID0 just slows things down except for maximum transfer rates. So if you just moved large files back and forth on your PC all day, that would be great, but I don't think that's what you're doing.

Oh, and you'd lose 130GB of space off the drive as well, if that mattered.

 

[killermiller]

Again, no. All you'll do is increase your maximum transfer rate and you'll probably see an increase in seek times(bad). Most benchmarks, tests, etc. show that running more than 2 drives in RAID0 just slows things down except for maximum transfer rates. So if you just moved large files back and forth on your PC all day, that would be great, but I don't think that's what you're doing.

Oh, and you'd lose 130GB of space off the drive as well, if that mattered.

I have 4 250GB 16mb cache drives in raid 0 and I had to RMA one and then I realized that would never have less. Each drive increased by HDTach about 60mb a second. It takes less then 2 bars for windows to boot when I first install and increases with all the crap that I install. They blow my 2 raptors 74GB 16mb's away. So I would have to disagree.

 

[JCLW]

What controller are you using?

All in all it looks fine.

Burst speed is pointless really, and depends on the controller and interface BUS (PCI, PCIe, Southbridge, etc) - not the drives.

RAID 0 just increases STR. And your average STR went from 55ish to 100ish, so that's about what you should be expecting.

Only way to increase seek times is to move to faster drives (ie: Raptors).

 

[tuskenraider]

They blow my 2 raptors 74GB 16mb's away. So I would have to disagree.

"blow them away", when you state hyperbole like that I just don't even know where to begin to discredit your post. Maybe you should do a little research about the greatly diminished accumulative effect adding drives to a 2 drive RAID0 array has. Or better yet, I would live to see your 3 vs. 4 drive data(measured in seconds not "bars"), showing how you boot quicker and open programs faster with more drives.

RAID 0 just increases STR. And your average STR went from 55ish to 100ish, so that's about what you should be expecting.

Only way to increase seek times is to move to faster drives (ie: Raptors).

Right on.