BARE facts on Macintosh speed FEATS


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Ultra320 15,000 RPM SCSI hard drives compared


Originally posted 06/06/03 by rob-ART morgan, mad scientist








Among the three drives, there was no clear winner. No matter which of the three drives you choose, it would be faster than the fastest Ultra ATA-100/133 drive and the fastest FireWire 800 drive kit.

Of the two brands we tested in a striped array, the Seagate Cheetah did best. (Stay tuned for an update where a pair of Fujitsus will be run in a striped array.)


If they're so fast, why isn't everyone using 15K Ultra320 SCSI drives in their Power Mac?

For one thing they are EXPENSIVE compared to Ultra ATA drives. The 73GB Cheetah we tested has a suggested retail price of $806. But let's say you buy one at a discounted $684.99 from The 80GB Hitachi 180GXP Deskstar Ultra ATA-100 drive costs only $83.50 at GoogleGear. That makes the Cheetah 8 times more costly after discounts. The Ultra320 PCI host adapter is expensive, too. The ATTOTech dual channel UL4D we used runs $549. The SonnetTech dual channel Tempo ATA-133 runs $99.

Then there's the size issue. The biggest 15,000 rpm Ultra320 SCSI available is 73GB. The Ultra ATA-100/133 drives are available up to 250GB.


So what's so special about Ultra320 SCSI drives?

Although 15,000 rpm and 3.6 ms average seek time is nothing to sneeze at, the biggest advantage has to do with the interface. Ultra320 means that each channel of the controller supports transfer speeds up to 320MB/s. When I did the striped pairs, I put each drive on its own cable connected to a separate channel. When I put two drives on the same cable and same channel, I got the same speed.

I could have put four drives on the same channel without any bottleneck in speed. (I can't give you those numbers until I pick up a four connector cable from Frys.) Put 8 drives on a dual channels and you'll be cruising along at up to 640MB /s. Get the point?

Reliability? Both Ultra SCSI and Ultra ATA drivers have the same non-recoverable error rate. However, all three Ultra320 SCSI drives come with a 5 year warranty. The Ultra ATA drives with 8MB buffers come with 3 year warranty. Those with smaller buffers come with 1 year. That would imply that the manufacturers believe their Ultra320 SCSI drives are more bullet proof than the Ultra ATAs.



The Ultra320 drives tend to run hotter than Ultra ATA drives. Our lab has no way to measure temperature. But Storage Review measured all three drives in a controlled environment. The Maxtor Atlas measured the hottest at 30.8 degrees Celsius. The Cheetah ran coolest at 25.1 degrees C.

Compare those numbers with the Hitachi Deskstar that runs at 22.1 degrees C. The Western Digital 2000JB runs at a relatively cool 19.7 degrees C.

As for noise, the Cheetah was quietest of the SCSI drives at 45.1 dB/a. The Fujitsu was noisiest at 50.5 dB/a.

The quiestest SCSI was as loud as the loudest of the faster Ultra ATA drives. The Western Digital 2000JB generates 45.5 dB/a. The Hitachi-IBM Deskstar is much quieter at 40.1 dB/a. The Seagate Barracuda ATA-V is the quietest of all at 37.8 dB/a.

If you are running a sound lab and noise is an issue, you need to take a look at the CoolMac Silencer from CryWolf. It will reduced your total system noise to 35 dB/a.




Storage Review has an article showing the Fujitsu and Maxtor 15K Ultra320 SCSI drives giving the Cheetah 15K.3 fits. Their results differ from mine. They use a Windows PC testbed and Windows benchmarks.

Storage Review tested the Western Digital 250GB 7200rpm (WD2500JB) Ultra ATA-133 drive against four other top Ultra ATA drives including the Hitachi-IBM 180GXP and Maxtor DiamondMax Plus 9.



The test computer was an Apple Power Mac G4/1.42GHz Power Mac running OS X (10.2.6). The striped arrays were created using the OS X Drive Utility RAID function.

The Ultra320 PCI Host Adapter (controller) was the ATTO Technology UL4D. It can be purchased direct from ATTO's online store.

The Ultra320 SCSI drives tested included:

Seagate's Cheetah 15K.3 (ST373453LW) available at discount from

Maxtor's Atlas 15K available from the MaxStore.

Fujitsu's AL 8LX (MAS3735 NC/NP) currently isn't available from the Fujitsu Online Store but I'm sure it soon will be.

SEE "HOW WE TEST" for details on the tests reflected in the graphs.



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© 2003 Rob Art Morgan
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