We Have a Winner – Seagate’s ‘Cheetah X15’ – THG.RU

Get Ready for Seagate’s High-performance Drive

It took a while before Seagate provided us with the Cheetah X15, one of their fanciest hard drives. The Cheetah series of drives has been groundbreaking in its own right – several years ago, the first model in the series was also the first to break the 10,000 rpm barrier. Increasing the rotation speed is one of the most popular ways of improving hard drive performance. Today, every SCSI hard drive manufacturer ships at least one family of drives that runs at 10,000 rpm, which has become the current standard for high performance SCSI drives. In the IDE sector, 7200 rpm is the current standard, but perhaps it also won’t be long until we see the first 10,000 rpm IDE drives.

15,000 rpm Drives: A Balancing Act in Design

There are basically two ways to increase the performance of hard drives: increase the rotation speed or increase the data density. Increasing the rotation speed definitely enables better sequential performance, but only if you adjust the read/write mechanism accordingly. Increasing data density is also a popular method – recently, Western Digital announced the first drive with 27 GB per platter, which is in strong contrast to the 15 or 20 GB per platter for most IDE drives and a greater contrast to the even lower densities for most fast-spinning SCSI drives. However, the catch is that high density doesn’t allow top rotation speeds, and vice versa. So essentially, designing a fast hard drive involves creating the most ideal balance between rotation speed and density.

Data Transfer: Not faster than 10k drives?

The maximum transfer rate of the Cheetah turns out to be less than that of the latest 10,000 rpm drives from Fujitsu and Quantum, a result that will probably disappoint many of you. Is it really possible that the most technically sophisticated hard drive could perform below the current 10,000 rpm top models? The answer is ‘yes’, and the reason, as explained in the previous section, is that hard drive engineers sometimes have to sacrifice a bit of data density in order to reach high rotation speeds – that’s exactly the case with Seagate’s high-speed drive. Is this necessarily a bad thing? Not if the drive runs at 15,000 rpm.

As you know, the outer areas of the platters move much faster than the inner ones, resulting in better transfer performance for these areas. By increasing the rotation speed, the performance naturally improves for the inner areas as well. So even though the Cheetah X15 has a low data density, the high rotation speed helps to keep the minimum transfer rates for these inner areas at a very high level. More on that later.

Noise Level: No Louder Than 10k Drives?

The noise measurements provide the next surprise – although the drive rotates at a much higher speed than drives we tested before, it produces even less noise than the others! Not only is there no high-frequency noise (unlike many of the older 7,200 and 10,000 rpm drives), but even the access noise is insignificant. However, the frequency of the access noise will make it seem louder to many people than the Fujitsu and the Quantum drives.

I was also quite pleased to see that this 15,000 rpm drive caused no vibration whatsoever. If you run it next to a Seagate Barracuda ATA (a first generation 7,200 rpm drive that was formerly our reference drive and caused heavy vibrations), you will find it hard to believe that it is running at such a high rotation speed.

Access Time: Definitely Faster Than 10k Drives!

The access time is an important factor, which I’ve saved for last. This aspect can be split into two parts: the seek performance (including head positioning) and the access performance. Of the two, the seek procedure takes more time, as it positions the read/write heads over the corresponding cylinder/track. Then the drive has to wait with the initiation of the read or write procedure, until the disk has rotated so that the requested sector is directly below the read/write heads. Obviously, the delay time depends on the rotation speed, which is the shorter the faster the disk the rotates. This is why the Cheetah X15 has the world’s shortest access times.

Technical Data

Test Setup

Benchmarks – Data Transfer Speed

As I mentioned before, the Cheetah X15 is obviously unable to reach the high maximum transfer speeds of the two other drives, even though the latter only run at 10,000 rpm. If you’ve read the entire article, you will know that this is due to the data density, which, because of the drive’s high rpm, is much lower than the Fujitsu and the Quantum drives.

However, the minimum transfer speed of the Cheetah is where you can really see the advantage in having an amazing 15,000 rpm. While the two 10,000 rpm drives cannot sustain their high data rates and inevitably drop to 23 and 20.5 MB/s, the Cheetah X15 never falls below 30 MB/s. This result, in my opinion, is much more impressive than a high maximum transfer speed.

Data Transfer Diagram

Business Disk Winbench

The Cheetah X15 rocks! A performance gain of approximately 25% for business applications is quite significant.

Highend Disk Winbench

The results of Ziff Davis’ Highend Disc Winbench are equally impressive. Again, the ST318451LC is able to bring 25% more disc subsystem performance than the other two drives.

Access Speed

Noise Measurements

As mentioned before, the Cheetah X15 can almost be called a quiet drive, considering that it runs at an extremely high rotation speed. In Idle mode, the drive never exceeds the noise level of the the two 10,000 rpm drives.

The levels of access noise are generally lower as well, but it sounds very aggressive subjectively, and the noise can only be reduced if you install the drive in a well-insulated case. However, since the Cheetah drives are not meant to be used in desktop systems, the noise factor is not as much of an important consideration.

Drive Temperature

As expected, the drive clearly becomes hotter than any standard desktop drive. Due to the high friction at 15,000 rpm, it will quickly exceed the temperature of 58°C that we measured after ~30 minutes.

In any case, you should generally make sure that every drive running at 10,000 rpm or higher is properly cooled. Even if the drive might run within an acceptable temperature range, you can definitely increase its lifetime by cooling it.

Conclusion

Let’s be honest: Did we expect these results? Basically, no. Most of us certainly expected a drive with transfer rates that could break all known records. Instead, we got a technically sophisticated drive with optimized overall performance.

There might be other drives that can beat the Cheetah X15 in terms of maximum data transfer rates, but hardly any drive will outperform this high-tech model in any real world benchmark – the Seagate dominated both the Business and the Highend Winbench, as well as the access time tests.

These benchmark results, in addition to the extremely high minimum transfer rate, make the drive perfectly suitable for all kinds of high-end applications. As an added plus, its makes only as much noise as typical 10,000 rpm models.

$410 is still a high price for a drive that stores only 18 GB, but if budget is not your most important concern, then it is definitely the best choice for high-performance drive arrays.