Cheetah 18 GB Ultra2 10k SCSI HD Raid 0 Perfornance

H

HitmanZ

Gawd
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Jan 22, 2004
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Hey guys,
well i have 2 Seagate Cheetah 18 GB Ultra2 10k SCSI HD ST118202LC drives in raid 0 hooked up to a mylex extremeraid 1100 Ultra2 2 port scsi raid controller with 32mb ram. When i connect 1 drive to this hdtach benchmarks rates it as 32 mb/ burst and 16mb/max. When i connect it to my usual raid 0 (both hds) it hits around 64/mb burst and 33mb/max. I was just wondering how these 10k cheetahs in raid 0 can't beat my brother's 40 gig 7.2k ide hard drive. I mean that thing gets 90mb/burst and like 52mb max. I tried another benchmark such as sandra and results still are low. I was thinking it was the controller but can anyone give me their bechmarks (better if it's the same type). Feedback appreciated.
 
ditto.........old drives.......don't have the xfer rates of the newer scsi drives...

I have Maxtor Atlas10k IV's and they only push 55mb/sec max read/writes....

When I put 4 x in a Raid 0 array I can get 200mb/sec read/write

any of the new 15k U320 drives should be able to push closer to 72mb/sec for a single drive, more in raid setups...
 
scsi2 has a theoretical bandwidth limit of 40 mb/s iirc. you're doing pretty good in those terms. newer drives will definitely be better. the one thing which you probably beat him at is seek times. scsi always wins at that. a raid1 setup with these drives might be better for a boot drive or something, but other than that... i'll take them off your hands :D
 
Hitman, I would still rather have your setup then your brothers, don't forget you are redundant and also I bet your scsi's have a better seek time then his 40g 7200 drive.
 
It's the drives. They're just old. Your controller's got 2 80MB/s ports though. That's enough for the Seagate Cheetah 15k.3 I'm running. It's a year old now, so I assume there are faster drives out. That controller should be able to stomp your bro's drive w/ just one drive hooked up, but you'll need a new drive.
If you want to smoke your bro's drive I'd say get a new(er) drive for your OS & apps, then mirror the two old drives and keep your important stuff on 'em. Move it off or replace the dead one if one fails though... those disks are getting pretty old.
 
He's running raid 0 nothing about raid 0 is redundant period. No fail safes at all.
 
my 15k.3 cheetahs get like 85mb/s each :D

and sandra is a crap benchmark, it sais my 15.3 is slower than like ATA33 even tho every other benchmark shows it at 80~85MB/s
 
I see, but i was thinking even at 7 years old, these mofo's spin at 10,000 rpm so i thought i would get AT LEAST better transfer rates than any 7.2k ide drives. Yes, they do have much better seek times. Thanks for all your help guys. I really appreciate it.
Thanks again!
 
The catch is transfer rate is basically rpm x density, and the data density on new drives is far higher.
 
That's a common misconception. When drives are revved up to higher spindle speeds the manufacturers usually use smaller-sized platters. Use of those smaller platters puts less strain on the motors, produces less heat, and makes access times faster since the arms don't have to travel as far. However, smaller-sized platters also mean lower areal density, and that, in turn, means fewer bits go by per rotation. In addition to that, areal densities are constantly increasing - manufactureres need this to increase capacities, increase contiguous transfer rates (this is predominantly how IDE drives get faster), and most importantly, lower costs.

So your brother's IDE drives, being far newer, may be using platters with three or four times the areal density as your old SCSI unit. The 50% increase in spindle speed doesn't make up for that much difference in density, resulting in his faster contiguous transfers. Your SCSI drive will still have faster seek/access times, however.
 
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