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Seagate Cheetah 15K.6 Hard Drive
Date: Sep 02, 2008
Author: Chris Connolly
Overview and Specifications

Traditional hard disk storage is living on borrowed time. We know it and storage manufacturers know it. Solid state drives, which use non-volatile memory chips instead of rotating metal discs for storing data, are simply a better medium in the long run. They consume less power, create nearly zero heat, and produce no noise – but best of all, there are no moving parts to wear out over time. The technology and prices aren’t quite there yet, but it’s only a matter of time. Take a quick look through any tech-oriented forum and you will likely run into folks proclaiming the death of traditional platter based storage. For the most part, they're right - but there is a twist to the story as platter based storage manufacturers are fighting back.

There is still plenty of life in traditional storage technologies, and Seagate is out to prove that. In fact, Seagate is out to show that not only can their new line-up of high-end hard disks provide better cost per gigabyte ratios compared to SSDs, but it can also run circles around many of the current SSD offerings, in raw read / write performance. Many folks are under the assumption that SSD’s are the end-all, be-all of high-performance storage. While SSD’s are excellent in terms of seek times, digging deeper shows that their read / write speeds are sometimes lacking compared to today’s high-end hard disks.

With their newly launched Cheetah 15K.6 hard drives, Seagate is looking to bust the doors off of the performance numbers people expect to see with platter-based storage. Some quick numbers to whet your appetite – most desktop level (7,200 RPM) hard drives have sustained transfer rates of about 50 - 60MB/s, where newer models are reaching 70-80MB/s. Typical high-end 10K hard drives can push upwards of 100MB/s. This new Cheetah 15K.6, however, claims to offer up to 170MB/s sustained throughput, surpassing what’s possible with many solid state hard drives currently (though a new generation of SSDs from Intel and others will take SSD performance up a notch again soon). In addition, the Cheetah 15K.6 is over 25% faster than previous generation 15K.5 disks.

Seagate is eager to show what these new discs are capable of, so we’ve got a special treat for all you HotHardware readers. Not only do we have the new Cheetah 15K.6 in house for testing against a load of other enterprise-class hard disks, but we’ve got a pile of them. Not only do we have performance numbers of the 15K.6 in a single drive installation, but we’ve got numbers with them running in high-end RAID-0 and RAID-5 configurations, to show performance scaling capability as well. For those who say platter-based storage is breathing its final breath, you might reconsider that notion.  Read on...

Four Seagate Cheetah 15K.6 450GB Drives - 1.8TB of 15,000 RPM luxury storage.

Best In Class Comparisons

Before we look at the Cheetah 15K.6 in greater detail, it’s worth a quick look at the environment which this drive is entering into. If you’re looking at the ultimate in performance in a particular class, here are a few solid options currently on the market in different mediums, for a spec and price comparison.

  Best In Class Performance SAS HDD Best In Class Performance SATA-II HDD Best In Class Performance SATA-II SSD
  Seagate Cheetah 15K.6 Western Digital VelociRaptor OCZ Core Series
Peak Capacity 450 GB 300 GB 128 GB
Street Price $800 $300 $499
Price Per Gigabyte $1.7 / GB $1.0 / GB $3.90 / GB
Sustained Read Speeds 171 MB/s 120 MB/s 143 MB/s
Spindle Speed 15,000 RPM 10,000 RPM N/A
Cache Memory 16 MB 16 MB N/A
Average Read Seek Time 3.4 ms 4.2 ms 0.1 ms
Average Write Seek Time 3.9 ms 4.7 ms 0.1 ms
Average Latency 2.0 ms 5.5 ms 0.1 ms
Interface Serial Attached SCSI 3 GB/s Serial ATA-II/300 Serial ATA-II/300
Acoustics 36 dBA (Idle)
Unknown (Seek)
29 dBA (Idle)
36 dBA (Seek)
0 dBA (Idle)
0 dBA (Seek)
MTBF 1.6 Million Hours 1.4 Million Hours 1.5 Million Hours
Warranty 5 Years 5 Years 5 Years

As we can see, the Cheetah 15K.6 drive currently holds a pretty sizable lead in terms of sustained read speeds over one of the fastest SSDs currently available, and can do so at a lower price per GB ratio compared to high-end SSDs. Of course, SSDs have the inherent advantages of exponentially lower seek times, zero noise, and much lower power consumption. We should also note that Intel's branded SSD product line is going to hit the market soon and is expected to have disk read speeds up to 250 MB/s, but as of today, they are not available for purchase.

The Cheetah 15K.6 drive is nearly double the cost per gigabyte compared to Western Digital’s newly launched VelociRaptor product, but considering the performance differences between the two, this is not too surprising. One must also factor in the cost of a SAS controller board for the 15K.6 drives, which our SATA-II drives don’t have to deal with as well, which is also added cost if you're coming from the land of SATA-based storage. Let’s look at the Cheetah 15K.6 closeup, next.

Drive Details

Visually, Seagate’s Cheetah 15K.6 drives are not that striking. There aren’t any major design changes in terms of the drive design compared to prior generation Cheetah 15K.5 drives. The aspect which we can’t convey visually is that these drives definitely feel enterprise class – in that they are much heavier than a traditional desktop hard drive. As high-end SCSI drives such as this are designed for usage in enterprise-class workstations and servers, they have far greater reliability ratings and have greater thermal tolerances too. This particular model is Seagate’s high-end model, in terms of speed and capacity, with a massive 450 GB of storage space. For a 15K drive, this is monstrous – and roughly three times the capacity of most manufacturers' solid state drives (most peak at 128GB, currently).

Seagate Cheetah 15K.6 - Top

Seagate Cheetah 15K.6 - Bottom

So, what IS this thing? Let’s break down the specifics. The Cheetah 15K.6 is a 15,000 RPM hard disk which runs on a Serial Attached SCSI 3 GB/s (SAS) connection. Fibre channel is an option as well, but Serial ATA is not, which means that if you want to run one of these new disks, you’ll need a SAS controller card. SAS controller cards can be had for under $100 on the low-end, but if you want a true hardware RAID controller, you should be prepared to shell out at least $300 for a four-port card.

The Cheetah 15K.6 sports capacities up to 450 GB at the high-end, but also comes in 300 GB and 150 GB flavors. As the 15K.6 is a quad-platter drive (with eight read heads), this means that each of the 15K.6’s platters is sporting a capacity of at least 113 GB, although full capacity of the platters is unknown. The Cheetah 15K.6 is utilizing Seagate’s second generation perpendicular recording technology, the first generation being the X15.5.

Seagate’s specifications show idle acoustic levels of 36 dBA and power consumption levels of 17W when writing, which are indeed high on both counts. For comparison, most traditional desktop hard drives run at about 26 dBA with power consumption levels of 7-10W – but as we’ve said before, this is no traditional hard drive. Seagate claims that this drive has the best numbers in terms of IO’s per second (per watt), a statistic we haven’t seen before, but one which is certainly valid in this day and age of power consumption. How they can claim this in comparison to SSD’s, which can deliver tremendous IO’s at incredibly low wattage is somewhat unbelievable, but compared to traditional SATA hard disks, Seagate might have a point.

Amazingly, for a drive of this speed, Seagate only equips the Cheetah 15K.6 with 16 MB of cache memory. This seems to be standard for Seagate’s enterprise class drives, as they have maintained solid performance all along with this healthy (but in this day and age, not that impressive) 16 MB of cache. While many high-end desktop drives are being equipped with larger 32 MB cache buffers, one thing to keep in mind is that for enterprise class SAS hard drives, you’ll likely be using them with a RAID card with its own cache memory. For example, the Adaptec SAS card we used is equipped with a huge 128 MB of cache by default – so having 16MB of cache is not a huge turn-off for us. Obviously, it’s not hurting their performance numbers – and for a drive of this caliber, if adding extra cache would have greatly helped performance, they would have put it on. Cache is (relatively) cheap – so the 16MB cache buffer size was likely sized for this drive purposefully.

The 15,000 RPM spindle speed not only helps with sustained throughput, it also helps with seek times. While not as impressive as the ~0.1 ms seek times of solid state hard drives, the Cheetah 15K.6’s 3.4ms average seek time is unbeatable when it comes to platter-based storage. Average latency is an impressively low 2.0ms. In plain English, this means that when you want your data, it’s going to be able to find it damn near instantly.

Seagate backs this drive up with a standard five year warranty, and tags this drive with a massive 1.6 million hour MTBF (mean time between failure) rating. Typically, most enterprise level hard drives (and most SSD’s) have 1 million hour MTBF ratings, so this shows that Seagate is going above and beyond with these drives. Thanks to Google calculator, we can share with you the following statistic. 1.6 million hours = 182.527284 years. Looks like your data will be safe for a while. For those weary of other eyes seeing your data, Seagate also offers a self-encrypting drive option, however this is only available to OEMs at this point.

Heat and Power Consumption

Heat and Power Consumption

With a maximum power consumption rating of 17W and peak idle decibel level of 36 dbA (seek/write decibel levels are not listed in its spec sheets), the Cheetah 15K.6 appears to be a somewhat scary drive in terms of specifications. In short, it sounds like it will run hot and loud, which is exactly what most are trying to get away from in their systems. Low heat and noise are two of the main factors why solid state hard disks are so appealing.

Let’s start off with heat. In order to test the heat of the Cheetah 15K.6, we ran an Iometer stress test on each drive after their normal testing was finished, and measured the temperature of the drive on both its side and top. The Iometer stress test uses the “Database” pattern and runs for 30 minutes. Unlike most high-end (10K+) hard drives, the Cheetah 15K.6 has no integrated heatsink functionality, meaning it is relying solely on the environment and cooling around it. The drives were tested in a temperature controlled room at 78F with no active cooling.

We were honestly very surprised to see that the Cheetah 15K.6 performed so admirably here. Throughout most of our testing, the 15K.6 did not appear to get very hot, only lukewarm in most scenarios. Of course, once you bundle them up closely in a rackmount, thermal issues may become apparent, but this is true for any high-end hard disk. For the most part, we believe Seagate’s claims of performance per watt appear to be true, as the drive is very tolerable in terms of heat for a 15,000 RPM unit, and potential buyers shouldn’t be scared about this fact when considering one of these drives. As for power consumption, we tested these enterprise class drives in their normal fashion. We attached a hardware wattage monitor to the system which monitors the wattage load of the entire system (not just the hard disks). We read the total system power consumption numbers with each hard drive in idle mode (after Windows bootup, after everything has loaded and spin down) and during full load (performing a disk intensive Iometer test). Full system specifications for the surrounding components can be seen on the following page.

Our power consumption numbers for the 15K.6 and ES.2 SAS drives are somewhat higher due to the additional power consumption of the SAS controller card in the mix. In any case, the power consumption numbers aren't too bad here, as our 15K RPM drive with a SAS controller consumes about 20-30W more compared to our 10K RPM hard disk. This is to be expected, but the results are not too bad.

The final environmental aspect is noise, which I feel is the largest concern. Heat issues can be solved fairly easily by using a case fan (assuming you’re not in a tightly packed rackmount) and power consumption issues aren’t too bad (again, true for rackmounts, but high-wattage desktop power supplies are fairly cheap). Noise is a harder issue to deal with though, and its stated 36 dBA noise level is certainly high.

Luckily, Seagate appears to be fairly conservative here as well. The Cheetah 15K.6 first makes itself apparent during the initialization of your SCSI controller, where you’ll hear the drive quickly ramp up from producing zero noise to its idle level. With a single Cheetah 15K.6 drive, the noise level isn’t that bad, but with multiple drives, they definitely become noticeable in any sort of reasonable low noise environment. As for read/write noise levels, thankfully they were much lower than anticipated. The drives are audible when performing disk intensive operations, but not to the point where we would consider them a nuisance. The noise levels were above our ambient level, but the pitch was low, which makes it fairly easy to tune out. Interestingly enough, the noise levels which we noted on the Cheetah 15K.6 were lower than our Raptor 10K drives, which have a lower “rated” decibel level. Western Digital’s newer VelociRaptor drive, however, was definitely quieter than the Cheetah 15K.6. As someone who is extremely noise sensitive, it wouldn’t pain me to put one or two of these drives into a personal workstation and sit by them, day in, day out.

Testing and Windows Vista Performance

In order to test these drives properly, we brought in Adaptec’s new 3400-series Serial Attached SCSI RAID card. This model runs about $400 at most retail stores, and is equipped with a PCI Express x4 interface with 128 MB of DDR2 memory as its cache buffer. It supports all the well known RAID levels, and  some which are relatively unknown. According to its docs, it supports RAID levels 0, 1, 1E, 5, 5EE, 6, 10, 50, 60, and good ole’ JBOD if you just want to run them as standard hard drives. It is equipped with a hardware RAID processor which requires a dedicated heatsink, which gets toasty (understatement) warm during testing. It also has a nifty SAS 8087 connection at the end, which combines four SAS cables worth of data into a single connector, and splits them out when you get to the individual drives – helping to keeping your chassis internals nice and clean.

We should also note that these tests were delayed by one month due to a faulty firmware revision on our first batch of drives. Seagate claims that these drives are not shipping to market in large volumes of yet, so drives with the early 003 firmware should not be hitting consumers' hands. Our full tests were done with the later released 004 firmware, which performed perfectly. If your 15K.6 drives have the 003 firmware, be sure to run disk write benchmarks to see if you have any performance anomalies.

For testing, we ran a series of benchmarks with our drives as a secondary hard drive (in order to keep the discs clean from OS level performance degradation) – along with a series of tests with the OS on the drive itself in order to test real world performance scenarios.

Test System Details
Specifications and Revisions

  • Intel Core 2 Quad QX6700 (3.0 GHz) Processor
  • XFX Nvidia nForce 780i SLI Motherboard
  • 4 x Kingston XMS DDR2-800 Memory (4 x 1 GB, CAS 4-4-4-12)
  • 1 x Nvidia GeForce 9600 GT 512 MB
  • 1 x Plextor PX-755SA DVD+/-RW Drive
  • 1 x Corsair HX620W 620W Power Supply
  • Windows Vista Ultimate Edition (32-bit with SP1)
  • Adaptec 3400 PCIe x4 SAS Controller Card (for SAS drives)
  • Seagate Cheetah 15K.6 450 GB (x4) SAS
  • Seagate Barracuda ES.2 1 TB SAS
  • Seagate Barracuda 7200.11 1 TB SATA-II
  • Western Digital VelociRaptor 300 GB SATA-II
  • Western Digital RE2 750 GB SATA-II
  • Western Digital Raptor 74 GB SATA
Windows Vista Performance
Windows Vista Ultimate Boot Time

With the operating system installed on each of the test hard disks, the Western Digital VelociRaptor drive was able to get into the operating system the fastest of our lot. Our 15K.6 and ES.2 SAS drives are held back by our SAS controller, which takes an extra minute during the boot process to start up and initialize. This particular controller was fairly slow in this regard, and most SAS controllers can cut this time down by about half. If you reboot your system a lot, keep in mind that SAS configurations do typically take longer to boot up.

For the record, once inside the OS, each of these drives was able to score a perfect 5.9 in Windows Vista's integrated "Experience" benchmark for storage performance.

HDTune Pro - Read Performance

HDTune Pro Storage Benchmark - Read Performance
Version 3.10 (x32)

In terms of disk read speed, the Cheetah 15K.6 delivers the fastest single disk performance we have seen to date. The drive delivered a maximum read speed of 166 MB/s (just shy of the stated maximum of 171 MB/s by Seagate) and a sustained transfer rate of 135 MB/s. Both of these numbers are substantially above our 10K SATA hard disk speeds, and are above what many of today's SSD hard drives can offer. The X15.6 also does well in terms of access time with a rated 6.0ms time, half that of conventional desktop hard drives.

HDTune Pro - Write Performance

HDTune Pro Storage Benchmark - Write Performance
Version 3.10 (x32)

With the latest firmware loaded, these drives performed terrifically in terms of disk write speeds. Our test showed a maximum 179 MB/s write speed on the X15.6, along with a sustained 137 MB/s, which is a solid 30%+ performance boost over the VelociRaptor drive. Once again, access times look great.

PCMark Vantage and Gaming

PCMark Vantage Vista Benchmark
Storage Scenario Benchmarks

Crysis Demo
Storage Focused Gaming Benchmarks

With an operating system installed directly on the test hard drive along with PCMark Vantage, we see how storage speed can affect overall system performance numbers. With the faster 10K RPM/15K hard drives, our PCMark Vantage numbers trend upward, with the X15.6 delivering the fastest numbers of the lot.

In terms of gaming performance, the Cheetah X15.6 drives don't really deliver anything significant over a modern 10K RPM hard drive. In terms of our game install and level load times, the X15.6 drive doesn't perform substantially better compared to lower cost alternatives, which leads us to recommend a much less expensive 10K RPM hard drive if you're interested in price/performance for gaming.

IOMeter - Single Disk Comparison

Workstation and Database File Patterns (IO's per Second)

The Cheetah X15.6 delivers solid overall performance in Iometer, as a single disk can deliver roughly 370 IO's/s at its maximum for the workstation pattern. The VelociRaptor is close in this pattern, delivering about 350 IO's/s. In our Database pattern, the Cheetah X15.6 struggled a bit under heavier loads, allowing the VelociRaptor to grab the performance lead in this particular IOmeter pattern. We were expecting slightly more from the X15.6 drives here, but this looks to be a case of the controller card holding back the drives slightly. When we loaded up multiple drives in RAID configurations, the Cheetah finally showed some muscle, as seen in the next page.

IOMeter - Multi-Disk RAID Configurations

Scaling Performance - Iometer
Workstation and Database File Patterns (IO's per Second)

These drives scale very well when it comes to Iometer. While a single drive maxes out at about 380 IO's/second, two drives scale up to 790 IO's, three drives up to 1100 IO's, and four drives up to a whopping 137O IO's. Even in RAID-5, our numbers look great across the board. The Cheetah drives tend to show their best performance numbers under moderate load.


Performance Summary:  Seagate's Cheetah 15K.6 is an impressive beast, and showcases what modern platter-based storage technologies are capable of. It's definitely a more brute-force approach to storage compared to modern solid state hard drives, but the end results are impressive nonetheless. This 15,000 RPM drive is capable of pushing between 160-170 MB/s speeds for both reads and writes, a very solid improvement compared to prior generations of high-end SCSI or SAS disks. Considering the drives are also capable of holding 450 GB of data, all in all, this is an impressive technological accomplishment. For comparison, our fastest reference 10K SATA drive (WD's VelociRaptor) only stores up to 300 GB of data and peaks at about 120 MB/s read/write speeds.


Of course, there are caveats with the new Cheetah. As you would expect from a drive that spins a series of metal discs at 15,000 RPM, it's not as silent as a desktop-class hard drive. In a closed case environment, the Cheetah 15K.6 drive is tolerable, but don't expect it to be very quiet. Also, it runs substantially hotter than traditional 10,000 RPM hard drives, but is certainly manageable with proper airflow. Also worth mentioning is that you will need a SAS controller in order to run this drive, which can run anywhere from $100 to $1000 on top of the price of the drive itself.  Interestingly enough, we've seen some information that more motherboard manufacturers will be integrating SAS controllers on desktop-class boards for their next-generation products, which reduces the cost of entry significantly, should this come to pass.

If you're putting together a high-end workstation or server setup, a couple of Cheetah 15K.6 drives connected via a high-end RAID controller can produce fantastic results. With our four-drive RAID-0 array, we were able to hit nearly 1400 IO's/second, which is pretty amazing for platter based storage, and should certainly be enough horsepower for most modern workstation scenarios. Three or four of these drives in RAID-5 delivers an exceptional performing setup with high reliability as well. These drives are built like tanks and have five year warranties. Given that there is still some uncertainly as to how SSD's will perform three, four, or five years down the line, we can imagine that traditional platter based drives such as this will still be popular in the high-end workstation and server markets.

While SSDs have made major strides in terms of upping performance and cutting costs, they currently don't match the price/performance ratio of a drive like the Cheetah 15K.6.  Assuming you don't have an issue dealing with the 15K.6's power consumption, noise, and heat production, the 15K.6 can deliver excellent performance and more capacity with Seagate's top of the line 450 GB model.


  • Top Notch Performance Numbers
  • Large 450 GB Peak Capacity
  • Low Random Access Times
  • Built For Reliability, 5 Year Warranty
  • Louder Than Most Spinning Drives
  • Higher Heat and Noise Production
  • Requires Costly SAS Controller

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