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IBM Ultrastar 18ZX DRVS18U2

  January 17, 1999 Author: Eugene Ra  
Evaluation unit provided by Dirt Cheap Drives

Early last year, IBM joined Seagate in the 10k rpm SCSI arena with the release of the Ultrastar 9ZX. For a brief time, the 9ZX reigned supreme as the fastest drive around, edging out the first-generation Seagate Cheetah 4LP. Only a short time later, however, Seagate started shipping the second generation Cheetah 9LP, which leapfrogged the IBM drive and once again garnered the Cheetah family the title. Today, a year later, the race continues, with IBM announcing a second generation 10k rpm unit and Seagate announcing its third. As was the case last year, IBM's entry shipped first. Here we'll take a look at the 18.2 gig Ultrastar 18ZX.

IBM 18ZXThere's a disparity forming between 10k rpm offerings between IBM and Seagate. Specifically, Big Blue seems to be lagging behind a bit in the areal density department. The Ultrastar 18ZX uses ten platters to deliver 18 gigs of storage. That's 1.8 gigs per platter, slightly more than the previous generation 9ZX. The upcoming Seagate 18LP (and newcomer Quantum's Atlas 10k) pack 18 gigs of storage on only 6 platters. Aside from the probable difference in sequential transfer rates (the Cheetah and Atlas STRs would likely be higher), the lower MB/platter ratio of the 18ZX necessitates a 1.6" form factor rather than the standard 1" profile that we like to stick to here at the Storage Review. This further ripples down in mechanics to seek time: 1.6" form factor drives tend to bring higher seek times to the table than their 1" counterparts, due primarily to more massive actuators. Actuators responsible for 20 read/write heads are subject to more inertia than those containing, say, 12 heads. The 18ZX therefore sports a relatively high 6.5 millisecond seek time (yes, we can't believe we're already calling a six-something ms access time high either!) rather than the 5.x ms seek time becoming the standard for this class of drive. So, a judgment call arises. Should we standardize on the 9 gig range and thus review the 9LZX and the smallest Cheetah 18LP (9 GB)? Or should we move to the 18 gig range, the natural successor to the 9 gig standard that Storage Review abided by last year? Fate played a bit in the decision here- we found the 18ZX more readily obtainable than the 9LZX. But we really do feel that we should move on to an 18 gig standard for SCSI drives. Remaining at 9 gigs simply to compensate for IBM's sub-standard areal density should have furrowed some eyebrows at any rate .

So, we've got (obviously) a spindle speed of 10,000rpm, a seek time of 6.5 ms, and 1.8 gigs per platter. This latest IBM drive, however, weights in heavy at the buffer. Four megs of buffer to be exact. Wow. As is the norm for SCSI drives, the unit is backed by a 5 year warranty.

As has been the case with many IBM drives, the 18ZX arrived to us with write-caching disabled. Adaptec's ThreadMark benchmark includes a cache-setting utility. As has been the case before, though, ThreadMark's utility wouldn't "catch." We'd enable write-caching, close ThreadMark, and recheck only to find it still disabled. Adaptec EZ-SCSI 5.0, however, did the trick. Once toggled on, write-caching remained enabled. Aside from this episode, installation of this Ultra2 SCSI drive went smoothly.

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Despite the shortcomings mentioned above, the Ultrastar 18ZX nevertheless managed to top the Cheetah 9LP in most test results. Performance of the IBM in WinBench 98 run under Win95 exceeds that of the Seagate by margins of 5%-7%. NT Business Disk WinMark performance is virtually identical between the two drives while High-End results have the nod going to the IBM with an 8% lead. ThreadMark results between the drives were very close.

As one would expect, the Ultrastar 18ZX ran warm to the touch even when running in our testbed's PC Power & Cooling Bay-Cool. Active cooling is a must for this drive. The 18ZX's noise was also par for the course: Seeks churned away with the best of them, every bit as loud as previous generation models. Notably, however, we found the high-pitch whine of bearings a little less pronounced with the 18ZX than other 10k rpm units.

Though the Ultrastar 18ZX captures the title of the "fastest shipping drive" (Hitachi, when will you ship that Pegasus?? The competition isn't standing still!), we can't help but be a little disappointed with its performance overall. We're witnessing very "evolutionary" performance increases here. Just enough here and there to pull ahead of a design from a competitor that's been shipping for almost a year. Seagate and Quantum are preparing to ship more ambitious designs featuring nearly double the areal density, along with the accompanying lower seek times and smaller enclosure sizes. Though they're still vaporware at the moment, drives from these competitors will allow everyone to better measure the progress that IBM's made in it's 10k rpm design.

IBM Ultrastar 18ZX DRVS18U2
Estimated Price: $1199.99
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* Note: Threadmark 2.0 and WinBench98 test results are the average of five trials.
WinBench99 test results are the average of three trials.


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