Actually, while Seagate's little white paper doesn't explicitly say so, the FLASH is used for a write cache and that provides one of the major benefits: Writes to the disk rarely need to spin up the motor. Probably 90+% of all writes to disk will fit into the cache in a typical laptop environment (no, compiling OpenSolaris isn't typical usage…).
My guess from reading between the lines of the Samsung/Microsoft press release is that there is a mechanism for the operating system to "pin" particular blocks into the cache (e.g. to speed boot) and the rest of the cache is used for write buffering. (Using it as a read cache doesn't buy much compared to using the normal drive cache RAM for that, and might also contribute to wear, which is why read caching appears to be under OS control rather than automatic.) Incidentally, there's a nice overview of some algorithms (including file systems) optimized for the characteristics of FLASH memory that was published by ACM last year, for the curious (who happen to have access to either the online or their local library). <http://doi.acm.org/10.1145/1089733.1089735> Anton This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
