Specialized Desktop Hard Drives

I will begin my overview of the specialized hard drive market with the ubiquitous desktop disk drive. While just about any drive could be used in a desktop computer, the class is generally defined by what it lacks – compact size, power efficiency, exotic interfaces, special drive features, and high performance are all generally not required.

My survey did reveal a surprising range of devices, even given these limited requirements. Although no 5400 RPM drives are currently being sold for desktop use, there is (one) 10,000 RPM desktop drive! And a few of the larger drives are showing up with mondo caches – up to e32 MB! I bet these cache sizes will put the squeeze on hybrid drives…

Really, desktop drives are mostly notable for what they are doing to the enterprise market, which I’ll cover tomorrow. But for now, click through for the full story on the desktop drive market!

Segment Differentiators

Unlike other drive types, desktop drives are mostly defined by what features they lack rather than what they offer. Although just about any drive can be used in any system, price-conscious desktop users typically find a large 3.5″ 7200 RPM drive under the hood. Mainstream systems use drives with 8 MB cache, but 2 MB, 16 MB, and even 32 MB alternatives are sometimes found as well.

Parallel ATA is still the dominant interface, but this is rapidly losing ground to SATA. In fact, most drive manufacturers have, publicly or privately, decided to stop producing PATA drives in the coming year. Surprisingly, nearly all SATA drives even in the desktop market now boast a form of command queueing! This was one of the features that was supposed to differentiate SATA and SAS, but it seems to have become a non-issue.  Note that the implementations are different, however, and the tests have not been overwhelmingly positive.

With nearly all desktop drives spinning at the same 7200 RPM speed, two differentiators have emerged: cache size and platter count.

Cache sizes range from the puny (2 MB) to the immense (32 MB). This can have a real impact on performance, as a large cache and the native command queueing feature common on SATA drives combine to allow the drive to continue servicing I/O requests while the drive is seeking. Most tests show that larger drive caches in general make a noticable impact on overall system performance.

Disk drives store information on spinning magnetic “platters”. These are read by heads, and can have data written on one or both sides. Although adding platters gives more capacity, it also adds weight, height, and especially heat output. The first manufacturer to reach a new capacity limit (250 GB, 500 GB, 1 TB) often does so by squeezing five platters into a single drive unit, but later offerings with fewer platters ought to be more reliable. Single-platter drives are much sought-after for their low temperature of operation, lower noise, and greater perceived reliability.

Specific Drive Offerings

There are lots of choices in the desktop field. As noted, just about any hard drive could be found in a desktop computer, but the following are specifically targetted to this market. Check out the Tom’s Hardware 3.5″ drive comparison table for lots of test information!

Note that only Hitachi and Seagate manufacture all parts of a hard drive these days. Fujitsu outsources wafer manufacturing and Western Digital buys the physical disk platters, but are otherwise quite integrated. However, Samsung, Toshiba, and Excelstor are little more than assemblers. This does not necessarily dictate which companies can be innovative, though. Samsung has surprised many in the market with their high-capacity SpinPoint drives, and Fujitsu has generally lagged the rest of the market. Note that Fujitsu and Toshiba are absent from the desktop market currently but are major forces in other market segments.


The Chinese manufacturer, Excelstor, is an also-ran in the disk drive race, with two lines of desktop drives (reportedly based on Hitachi technology) and one mobile offering. Their Jupiter Callisto is a small-capacity (40/60/80) 7200 RPM desktop drive. The non-Callisto Jupiter series is available in 80, 120, and 160 GB capacities on a single platter. Both offer PATA or SATA interfaces and high-tech features like fluid dynamic bearings and native command queueing, but with a 1-year warranty I wonder who is buying them. These are probably limited to the white-box integrator market with their low prices.


Hitachi Global Storage Technology’s Deskstar line comes in quite a few variants. Generally speaking, Hitachi’s older Deskstar line tells you the size of their platters with the model number. The 7K80 uses an 80GB platter, the 7K160 has a 160 GB, and so on.

This does not hold for the newer drives, however: The 7K250 line uses a 125 GB platter, and the 7K500 is available with 100 GB, 133 GB or 166 GB per platter. Hitachi was first to market with a half-terabyte drive (back in July of 2005) by spinning up five 100 GB platters in the 7K500 line. This was also the first desktop drive with 16 MB of cache as an option.

The jumbo 7K1000 series uses 4 or 5 187 GB or 200 GB platters for sizes of 750 GB and 1 TB. Note that Hitachi was first to reach this magic number back in April, but their 5-platter disk isn’t (well, actually, is) looking too hot compared to Seagate’s pair of 4-platter units and Samsung’s amazing 3-platter SpinPoint F1 drive.


Samsung doesn’t explicitly assign their SpinPoint drives to market segments, but a look at their product lineup shows that the SpinPoint P (mainstream) and SpinPoint T (three-platter) drives are appropriate for the desktop. Of course, their hybrid drive line is ultra-specific to Windows Vista, since that’s the only operating system that currently supports hybrid technology! SpinPoint V (AV-optimized) SpinPoint S (silent)


Seagate’s desktop line continues the long-standing Barracuda name. The company currently offers three series of drives, numbered 7200.9, 7200.10, and 7200.11, all with 7200 RPM spindle speeds. The single-platter 7200.9 models are targetted at OEMs and system builders, coming with 2 or 8 MB of cache in 40, 80, 120, and 160 GB sizes.

The 7200.10 was the first 3.5″ drive to use perpendicular recording to pack up to 250 GB onto each platter, a point they hammered home back in June. The 7200.10 was the first 750 GB drive on the market by a long shot, owning the greater-than-500 GB market from July 2006 through the beginning of 2007.

has been superceded by the new 7200.11 line in the high-capacity space. This new line offers up to 32 GB of cache and 1 TB of capacity (not yet released), though Hitachi beat Seagate and the rest to the punch at this magic number. Note that Seagate currently offers a 1 TB 7200.10 which uses four of the older-tech platters.

Seagate also sells a line of drives called just “Internal 3.5 Inch“, but these appear to be simply re-packaged Barracudas in retail-kit packaging.

Seagate bought Maxtor last year, but still offers the old Maxtor DiamondMax line, for the time being. Both the 20 and 21 series DiamondMax drives are sold in capacities from 40 to 320 GB. All run at 7200 RPM and the SATA versions offer native command queueing. The 20 series offers just 2 MB of cache in sizes of 40, 80, and 160 GB, while the 21 series features the more typical 8 MB cache and 160 GB platters for 250 and 320 GB capacities.

Western Digital

Western Digital’s Caviar line comes in four flavors for the desktop. The entry-level Caviar features just 2 MB of cache and tops out at 250 GB. Next up is the Caviar SE with its mainstream 8 MB cache and 320 GB maximum capacity. Top of the Caviar range is the Caviar SE16, which has 16 MB of cache and ranges to 750 GB (as of July). New to the line is the Caviar GP, Western Digital’s new “Green Power” high-efficiency drive, which ranges up to 1 TB and is only found in their MyBook external drive line (so far).

Western Digital also caters to the performance desktop market with the Raptor X. This speedy 10,000 RPM SATA drive is only available at 150 GB currently, but features a clear cover for all those clear PC nuts out there.


There is fierce competition in the desktop disk drive space, which opens the market to great opportunity. 500 GB drives can be had from a number of manufacturers for less than $150, and competition is heating up at larger sizes as well. Hitachi, Seagate, Western Digital, and Samsung are all rushing to one-up each other, so I expect to see a 1.3 or 1.5 TB drive on the market by the new year.

I found a few items of specific interest during my research:

  • Western Digital’s Green Power concept is likely to be copied by others, especially Samsung with their high-capacity platters. Although hard disk drives currently consume far less power than CPUs or graphics boards, a little extra power conservation never hurt. Plus, the external USB drive market is red hot and bus-powered 3.5″ drives are likely to appear soon.
  • Drive capacity expansion continues to outpace interface speed, but the switch to high-speed SATA is a welcome change.
  • Larger on-drive caches will likely make a heck of a lot more difference to system performance than hybrid drives.

Stay tuned tomorrow for my review of enterprise disk drive offerings!

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