Richard Elling wrote: > Erik Trimble wrote: >> Oh, and the newest thing in the consumer market is called "hybrid >> drives", which is a melding of a Flash drive with a Winchester >> drive. It's originally targetted at the laptop market - think a 1GB >> flash memory welded to a 40GB 2.5" hard drive in the same >> form-factor. You don't replace the DRAM cache on the HD - it's still >> there for fast-write response. But all the "frequently used" blocks >> get scheduled to be placed on the Flash part of the drive, while the >> mechanical part actually holds a copy of everything. The Flash >> portion is there for power efficiency as well as performance. > > Flash is (can be) a bit more sophisticated. The problem is that they > have a limited write endurance -- typically spec'ed at 100k writes to > any single bit. The good flash drives use block relocation, spares, and > write spreading to avoid write hot spots. For many file systems, the > place to worry is the block(s) containing your metadata. ZFS inherently > spreads and mirrors its metadata, so it should be more appropriate for > flash devices than FAT or UFS.
What I do not know yet is exactly how the flash portion of these hybrid drives is administered. I rather expect that a non-hybrid-aware OS may not actually exercise the flash storage on these drives by default; or should I say, the flash storage will only be available to a hybrid-aware OS. Has anyone reading this seen a command-set reference for one of these drives? Dana _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
