Solid-State Disk Lackluster for Laptops, PCs
SSD for the Enterprise
It is costly to optimize SSD for high-transactional operations, which requires sophisticated firmware and software within the drive's controller. STEC Inc.'s enterprise-class SSDs that it sells to EMC Corp. tout 52,000 transactions per second or input/outputs per seconds (IOPS). But a consumer-grade equivalent SSD drive achieves only 300 to 600 transactions per second, Forward Insights' Wong says. "It's not that they can't do better, but they aren't," he says.
Intel claims it has been able to mostly overcome the write-amplification and deliver 30 times more write performance to the host, or a 1.1 write amplification ratio. The company also says its new drives offer up to 35,000 operations per second. Grimsrud would not disclose how Intel overcame the write amplification issue, saying it is currently a "trade secret."
Gartner's Unsworth says Intel's flash drives use 10 channel controllers that optimize performance through interleaving the NAND flash memory chips in parallel for greater efficiency. Meanwhile, Intel's Grimsrud says the company's soon-to-be-released line of SSDs offers write and read speeds comparable to traditional hard disk drives.
Grimsrud, who was part of the team that developed the new High-Performance SATA Solid-State Drive product line, says Intel's laptop and PC SSD drives have up to 250MB/sec. sustained sequential read rates and 70MB/sec. sustained sequential write rates. The serial ATA SSD's random read rate is 35,000 IOPS and it has a random write rate of 3,300 IOPS.
So, applications that require more reads but fewer writes are seeing tremendous performance advantages through the use of SSD over traditional hard disk drives. In fact, most experts agree that SSD is far superior to using high-end, 15,000-rpm hard drives in Fibre Channel-attached storage devices.
According to Avian Securities' Cohen, high-end flash drives outpace high-end Fibre Channel drives at a 20:1 price/performance ratio because businesses must use as many as 20 15,000rpm hard disk drives in order to attain the random read performance of a single SSD drive.
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.