Solid-state disk lackluster for laptops, PCs

Laptops, desktops won't see a cost/benefit advantage in SSD for about two years

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For the cost of each short-stroke spinning disk drive that customers replace, "you could put 20 SSDs in," Cohen says.

SSD and laptop battery power

SSD is also touted to extend laptop battery life. However, most experts point to tests that show power savings through SSD equates to an additional five to 30 minutes on an average laptop -- the monitor and CPU eat vastly more power than a computer's drive. And some independent online publications have published results of tests showing some SSDs actually use more battery power than traditional hard disk drives.

Installing SSDs in laptops and PCs also requires Microsoft Corp. to update its operating system to take full advantage of NAND flash's attributes. The necessary changes were not included in the most recent service pack, and contacts within Microsoft have not heard of any progress coming in 2009, according to Cohen.

The reason SSD performance is not optimized is because the Windows operating system handles data in 4KB chunks. While SSD is also optimized to receive data in 4KB chunks, today's SSD drives are shoehorned into traditional hard disk drive bays, which receive data in 512-byte chunks, according to Forward Insights' Wong.

"It appears [Microsoft] is more focused on increasing PC touch-screen capabilities than NAND integration," Avian Securities' Cohen wrote in a recent analysis note.

Cohen believes the standards necessary to take full advantage of NAND and its capabilities within an SSD are just now beginning to flow through the various committees -- so full-featured products probably won't hit shelves till mid-2009.

Performance

Even vendors that sell SSD admit that when it comes to speed, there's little advantage at the consumer level (see "Performance showdown: Flash drives versus hard disk drives").

"Some SSDs out there are slower in writes than hard disk drives. It depends on how much you're writing at once. If it's 10MB, then it's probably on par with hard disk drives, but if you're talking 1GB, probably not," Gartner's Unsworth says.

Pat Wilkison, vice president of business development at flash memory maker STEC Inc., says the performance in SSD products varies greatly. STEC sells high-end flash memory to enterprise-class storage companies such as EMC, which uses the product in its high-end Symmetrix and midrange Clariion storage arrays.

"The class of product EMC needs is fundamentally different from what notebooks need," Wilkison says. "The reality is that performance varies depending on the applications running on it. Random write speeds are horrible. And guess what? As PC users, writes are important."

Western Digital Corp.'s fastest PC hard disk drive is the 3.5-in., 10,000rpm VelociRaptor, which has 300GB capacity. According to Computerworld's tests, the VelociRaptor racked up a 250.3MB/sec. burst speed, the highest we've ever recorded for a mechanical drive. Its average read/write rate was 105.6MB/sec. List price: $300.

Western Digital's fastest laptop drive is 2.5-in., 7,200rpm Scorpio Black, which has up to 320GB capacity. According our tests, the drive's average read rate is 63.8MB/sec. and its burst read rate is a screaming 238.8MB/sec. List price: $230.

In April, Computerworld tested two other top hard disk drives against the two top SSD drives at the time. The results showed little advantage for the SSDs.

The drives included the following:

These were the results:

HD Tach Throughtput Tests

  Burst Speed Average Read Random Access CPU Utilization
Crucial SSD 137.3MB/sec. 120.7MB/sec. 0.4ms 4%
Ridata SSD 71.2MB/sec. 55.1MB/sec. 1.6ms 1%
Momentus HDD 214.3MB/sec. 54.0MB/sec. 14.1ms 2%
Barracuda HDD 135.0MB/sec. 55.0MB/sec. 13.4ms 4%

Boot-Up Times (in seconds)

  Cold Boot Restart
Crucial SSD 39.9 78.4
Ridata SSD 31.2 58.4
Momentus HDD 39.1 55.6
Barracuda HDD 39.9 59.9
Testing software: Simpli Software HD Tach
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