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Seagate Cheetah X15-36LP
  July 19, 2001 Author: Eugene Ra  

Seagate Cheetah X15-36LP Available Capacities *
Model Number
18.4 GB
36.7 GB
* The benchmark scores presented in this review represent expected performance across the entire line.
Estimated Flagship Price: $699 MSRP (36.7 GB)
Evaluation unit provided by Seagate Technology.


Over a year ago Seagate, as usual, was the first to elevate drive performance to a new level with the introduction of the Cheetah X15. The X15 was the first drive to feature a spindle speed of 15,000 RPM and the first drive specified with a seek time below four milliseconds; as a result, the anticipation felt by both SR's staff and readers was immense. Three long months passed between the X15's February 23, 2000 announcement and its review here at SR. In the end, the wait was worth it. The X15 was by far the fastest drive around.

Since then, two other manufacturers have risen to the challenge by announcing 15,000 RPM units of their own. We reviewed the 36-gigabyte version of IBM's Ultrastar 36Z15 a few weeks ago- it proved to be a stellar performer in its own right. Fujitsu's MAM3367LP has proven to be a bit elusive; we're still trying to get our hands on one. In a recent poll, however, readers made it clear that the drive they were waiting for was the successor to the X15, Seagate's own Cheetah X15-36LP.

Which upcoming SCSI hard drive do you look forward to most?
  Poll Choices  
Fujitsu MAM3367LP
IBM Ultrastar 36Z15
Maxtor Atlas 10k III
Seagate Cheetah X15-36LP

Some may say that the X15-36LP pretty much reads like an evolutionary improvement over its predecessor. Spindle speed, obviously, remains at 15,000 RPM. Seagate specifies seek times at 3.7 milliseconds, a scant 0.2 ms lower than the X15 (note that the 18 GB model is specified at an insignificantly faster 3.6 ms). The X15-36LP features a notably improved areal density... while the original X15 had to use five platters to achieve its 18 GB capacity, the X15-36LP utilizes only four 9-gigabyte discs to hit its 36 GB flagship mark. Buffer size has also increased, doubled to 8 megabytes.

Available in 18- and 36-gigabyte capacities, the X15-36LP squarely targets the highest of high-end applications, areas where speed is of utmost importance. Though it has initially shipped with an Ultra160 interface, the family will migrate to Ultra320 as the improved SCSI interface starts to permeate the industry. Fibre Channel versions of the drive are also available. An enterprise-class 5-year warranty protects the drive.

Does the X15-36LP live up to the hype? Let's find out!

WB99/Win2k Low-Level Measurements

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Click here to examine the STR graph for this drive

The X15-36LP weighs in with a WinBench 99 measured access time of just 5.9 milliseconds, easily the lowest we've recorded to date. Subtracting 2 ms to account for the average rotational latency of a 15,000 RPM drives yields a measured seek time of 3.9 milliseconds, about 0.2 ms off of the 3.7 ms spec... not bad, especially for a Seagate drive . The original X15 turned in a measured access time of 6.8 milliseconds. As a result, in a backwards kind of way, the X15-36LP brings a significant improvement to the table; 0.9 milliseconds translates to a 15% overall access time enhancement.

Transfer rates similarly forge ahead into record territory with outer-zone measurements topping 60 MB/sec. The X15-36LP's smaller-diameter platters (2.6") minimize "decay," permitting sustained speeds in excess of 50 MB/sec over more than 80% of the disk and bottoming out at a still-impressive 45 MB/sec.

WB99/Win2k WinMarks

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Seagate's drive easily races past the competition when it comes to the Business Disk WinMark 99. The X15-36LP's score of 11.1 MB/sec shatters a record freshly set by IBM's Ultrastar 36Z15 by 11%. High-End Disk WinMark results are even more impressive- the Seagate's score of 31.6 MB/sec tops the Maxtor Atlas 10k III (another recent record-breaker in its own right) by 15%.

IOMeter Performance

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The X15-36LP continues its pace by posting record-breaking IOMeter scores. Heavy load scores in excess of 400 IOs/sec in all three access patterns propel Seagate's drive to new heights in our IOMeter indices (normalized averages of Light, Medium, and Heavy loads). Under a typical file server pattern, the X15-36LP bests the previous record-holder, the original X15, by 15%. In our workstation pattern, the drive tops IBM's Ultrastar 36Z15 by a healthy 10% margin. Finally, under a database pattern, the X15-36LP again tops its predecessor by 15%. Simply amazing.


Remarkably, decreased noise levels accompany the X15-36LP's new level of performance. Idle noises, both in terms of high-pitched whine and lower "hums," are quite unobtrusive when masked by our relatively quiet power supply and drive cooler. Just last week we were amazed at the Maxtor Atlas 10k III's low levels of idle noise... the X15-36LP approaches the noise floor offered by the Maxtor! Seek noise, while not as muted as the typical ATA drive, is nonetheless impressive. The sound is more reminiscent of a good 7200 RPM SCSI drive's seeks rather than the rumble the early 10k RPM drives exhibited.

The X15-36LP runs just short of being too hot to touch after running through our IOMeter suite (2 hours and 37 minutes of intensive accesses) in a drive cooler. This means that despite its lower platter count, the drive runs hotter than its predecessor. Though our testbed case is small and our cooler and power supply fans are quiet (and thus don't move much air), we nonetheless recommend careful installation to ensure that the drive runs within its operating temperature limits.

The Safe Buy Award

Simply put, this designation means we'd purchase this product without regret. Sure, there may be a slightly better, slightly faster, and/or slightly less-expensive model from a competitor, but you can't go wrong with this particular unit. This award is applicable, of course, to all units at the top of their class, but also applies to units that, though not quite best-of-class, provide a strong showing nonetheless. In conclusion, the X15-36LP delivers mightily on all fronts: the lowest access times, the highest transfer rates, the highest WinBench 99 scores, and the highest IOMeter scores that we've yet recorded. That it does so with lowered noise floors is all the more impressive. There are only two drawbacks involved. The first regards heat. Though its not nearly as hot as the scalding IBM Ultrastar 36Z15, the X15-36LP does seem to run hotter than its predecessor, somewhat disappointing considering its reduced platter count. Price is the other factor... the drive runs upwards of 40% more than a 10k RPM drive featuring the same capacity. These two quibbles, however, are minor indeed in the eyes of targeted users. Make no mistake about it, the Cheetah X15-36LP is the fastest hard drive one can buy for any and all applications. Period.

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