Seagate Cheetah 15K.3

Early this summer the firm announced its third-generation unit. "X15-36LP" always struck us as a bit unwieldy. Seagate has fortunately dubbed its latest as the Cheetah 15K.3, intuitive enough especially considering that their latest generation 10,000 RPM unit bears the name Cheetah 10K.6. The 15K.3 doubles the line's flagship capacity to a respectable 73 gigabytes through the use of 4 18-gig platters. 3.6 millisecond seek times and an 8-megabyte buffer round out the vitals.

The 15K.3 is the first Ultra320 SCSI drive to hit our testbed. Ultra320's most highly-touted feature, of course, is an increase in the throughput ceiling to 320 MB/sec. Keep in mind that the current transfer rate champion, Seagate's own X15-36LP, barely tops 60 MB/sec in its outer sectors. While figures like these threaten Ultra2 SCSI's 80 MB/sec limit, Ultra160's 160 MB/sec limit maintains plenty of headroom. It is only in multi-drive scenarios that 160 MB/sec limitations arise. Our base drive tests occur with a single unit as the only active device on the host adapter. In such a setup, any performance advantages that Ultra320 (along with the requisite higher-bandwidth 64-bit PCI slots) would deliver over 160 are negligible. For our performance tests, we're going to take advantage of the specification's backwards compatibility and run the drive in Ultra160 mode off of our current host adapter. Bear in mind that improved bandwidth is only one of the benefits that Ultra320 delivers. A host of improvements in protocol and error correction should elevate data integrity and device interoperability to new levels.

The 15K.3 incorporates Seagate's Fluid Dynamic Bearing motors, utilizing liquid rather than ball bearings in its spindle. It's little known that the X15-36LP also used FDB motors; for one reason or another, Seagate didn't publicize the feature. Perhaps the company feared that touting the new motor would undermine the reputation of reliability that the Cheetah family as a whole enjoys. In our opinion, usage of FDB motors indicates the reverse: fluid bearings are a mature, time-tested technology that may be integrated into the most demanding enterprise-class products.

With this generation Seagate is more than ever emphasizing 15K RPM performance per dollar spent. The company points out that a similarly priced 10k RPM drive, while delivering double the capacity, fails to deliver equivalent performance even if the drive is "short stroked" and half the capacity remains unused. Further, they argue, the 15K.3's doubled capacity over its predecessor halves the costs of supporting infrastructure such as cases, racks, and the rooms needed to store such arrays. Throw in the assertion that a drive's purchase price represents only 20% of its total cost of ownership and the premium one pays for a batch of these screamers is negligible.

What kind of performance does the 15K.3 deliver? Lets take a look!