by Avram Piltch, Online Editorial Director on December 11, 2008
The hard drive is the slowest component in any computer. In a world where processors, RAM, and video cards all shoot through data at lightning speeds, the mechanical hard drive with a rotating spindle that reads data off magnetic platters, like a turntable, is a dinosaur.
According to Intel, CPU performance is 175 times what it was 13 years ago, while hard drive performance is a mere 1.3 times faster than it was when Windows 95 first hit the market.
“What this does is create this huge bottleneck for the PC and for the user. You see that with the hourglass or the hard drive light going,” said Kishore Rao, product line manager for high performance SSDs at Intel. “You sit there waiting for it to get done, and that I/O bottleneck is slowing down systems.”
Enter the solid state drive. With data stored on NAND flash chips, rather than magnetic media, the drives offer the potential for exponentially faster read and write times, lower power consumption, and greater durability than mechanical hard drives. But do they work better?
To assess performance numbers, transfer rate (the amount of megabytes per second a drive can read) is critical, as is seek time (the number of milliseconds the drive takes to locate data). Because a computer’s drive spends most of its time opening applications and files, the read transfer rate is much more significant than the write transfer rate.
A typical notebook hard drive, running at 5,400 rpm, delivers read transfer rates of anywhere from 35 to 45 MBps, with random seek times of 12 to 18ms. A faster 7,200-rpm drive usually improves on these numbers slightly, while a power-saving 4,200-rpm drive will fare worse than a 5,400-rpm drive. By comparison, a high-performance SSD will have a read transfer rate of more than 100 MBps and a seek time below 2ms. One SSD we tested, the Intel X25-M, is rated at a 250-MBps read rate and less than 1ms seek time.
But speed isn’t the end of the story. SSDs come with cost and
capacity trade-offs. As of press time, notebook vendors that offered SSD as a configuration option were charging anywhere from $500 to more than $800 to upgrade from much larger default hard drives to 64GB or 128GB SSDs.