The Benefits of Hybrid Drives

feminazi writes "Flash memory is being integrated with the hard disk by Seagate and Samsung and onto the motherboard by Intel. Potential benefits: faster read/write performance; fewer crashes; improved battery life; faster boot time; lower heat generation; decreased energy-consumption. Vista's ReadyDrive will use the hybrid system first for laptops and probably for desktops down the road. The heat and power issues may also make it attractive in server environments."

Comments

Re:Old?

[nmb3000]

Windows creates an immense swapfile anyway - why not just get the system to do it on either a designated part of the hard drive, or on a USB 2.0 flash drive?

Actually, has anyone tried that? I expect you could see a decent increase in performance that way.

Windows' swapfile usage is pretty similar to the way Linux does swap, except that Windows uses a file instead of a partition. By default it's 1.5 times the amount of RAM installed in the system and is made all at once to ensure a contiguous file. On systems with plenty of RAM it's still good to have because it means the OS can commit to having plenty of memory for applications which request a lot, most of which they might never use. Without a page file 10-20% of physical memory is wasted because the OS has committed to having it (think Photoshop, etc).

I don't know how well the pagefile would work on a USB drive since if you're using much swap you're already seeing serious degradation. Besides, flash drives still suck at write speeds, being many times worse than even an old IDE drive. That's the biggest problem with integrating the two technologies I would think--making sure that you don't introduce bottlenecks due to stuff like that.

Re:Maximum Writes for Flash Memory?

[DDLKermit007]

An age old method called write leveling. In practice it usualy doesn't work since most people do it with USB thumb drives and/or flash memorycards which are all removed on a regular basis so the reader/writer of the media gets changed allot or the controler doesn't impliment write leveling. As such the write leveling never really gets done very well. With a system like this the write leveling would be exact and the flash memory would end up outlasting the moveing parts of the hard-disk. Also as parts of the card went bad the controler would skip over those sectors in the future which would lead to it working even longer. Even one part of a regular hard disk goes bad and your boned completely.

you're thinking of the wrong kind of flash...

[YesIAmAScript]

NOR flash (like the BIOS chip in your PC) is good for 1M writes or more.

But NOR flash is low density. An 8MByte NOR flash is large.

The flash that is being integrated into these drives is NAND flash. NAND flash is the kind of flash you use in your digital camera. NAND flash is high density.

And it is crap.

SLC NAND flash is good for 100,000 writes. But SLC is on the way out because it's only half as dense as MLC NAND flash. MLC NAND flash is good for 10,000 writes.

Are you scared yet?

That's a statistical measure, so often cells last longer than 10,000 writes before crapping out. And systems that use NAND flash use ECC (error correction codes) and wear levelling to try to hide the flash wearing out. It's complex, but it does work pretty well.

But a coworker made a flash burner app to wear out some flash on purpose. It wrote constantly. He able to wear it out in a couple days. It didn't wear out the entire flash chip, but that's when the flash started to develop sectors that were unusably bad, even with ECC.