With the introduction of hybrid drives (like the ones mentioned here, from Samsung), notebooks can get ultra-low power drives because they don't have to keep the hard disk running as much. Hard drives use rotating meda. The slower notebook drives rotate at 4200RPM. Typical desktop drives use 5400RPM and faster drives go for 7200RPM or 10,000RPM. Like high performance sports cars, the more RPMs, the more energy required.
Up until now, power-conscious ment smaller capacity (thus less energy to spin up) or variable speed drives which could spin faster when plugged into the wall but slower when running on battery power.
With hybrid drives, the approach is a little different. Commonly used data is cached in flash memory rather than on the rotating media. Flash isn't as fast and typically has slower write times. But it consumes a lot less power. Also, flash wears out after a while, although the typical number of writes is pretty high (~1 million sector writes typical). Performance is still an issue as well, since flash read is slower and, when you get out of the cache, you still have to wait while the drive spins up.
Other initiatives, like Intel's Robson technology (see this Wiki article) have used this combination as a one-two punch to speed up boot time. It works like this: you start the drive spinning up, but in the mean time, the first n megabytes worth of boot data is already cached in the flash. This means the boot process is well on its way before the drive spins up to full speed and then it can take over. If your OS were small enough, you could launch the entire OS without ever touching the rotating media.
Sad to say, this means that you don't get to look at the Phoenix logo quite as long during boot. But you can always stop by with a keypress...
Tim
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