Hybrid hard drives: what's not to like?
A flash stash for little cash
Flash-based SSD drives may be bloody fast, but they're also bloody expensive. For some road warriors, price is immaterial, but for most mortals — or for their employers — price is everything.
This is where hybrid hard drives come into their own, delivering better performance than traditional hard drives, but for only a small premium.
At today's cash-per-gigabyte prices, MLC-based NAND flash is priced at a whopping 22.3X premium compared with a 320GB 2.5-inch mobile hard disk drive, according to Aaron Rakers , an enterprise hardware analyst at Stifel Nicolaus.
There's no disputing that a flash-based notebook screams. A 2.4GHz MacBook Pro fitted with a Mercury Extreme Pro  SSD from Other World Computing , for example, booted and loaded Adobe's CS5 in 28 seconds while a 2.6GHz MacBook Pro fitted with a hard drive took almost 70 seconds: its faster CPU was defeated by flash.
But OWC suggests you fit the SSD as a system and application load drive, and keep your bulk data on an externally-attached hard drive. The reason is simple: it's too expensive to replace all those hundreds of gigabytes of hard drive capacity with flash.
An OWC 240GB Mercury Extreme Pro solid state drive is $649.99. You can buy a 250GB Seagate 2.5-inch, 7200rpm hard drive at OWC for $62.99, a tenth of the price. You really do have to be loaded to rip out the hard drive and replace it completely with flash.
But — and this is a big but — the main point of a notebook on the road is that you have everything in a single case. You are compromising your mobility if you travel with an SSD set up only for booting and loading applications. For your data, you'd need to lug an external drive and cable.
So let's turn to hybrid hard drives — Seagate's Momentus XT  is a good example. This sticks a 4GB flash drive into a 2.5-inch Momentus hard drive's enclosure. It's enough, Seagate says, to get system boot time down to within a few seconds of a flash boot drive and at a cost that's only $20 or so above the ordinary hard drive cost.
Replace your flash-less hard drive with this hybrid and you'll get a much faster-loading notebook at a much more reasonable price than with a flash boot drive, and you can take it on the road without additional cables and an external drive. What's not to like? ®