On Tue, Feb 10 at 16:41, Jeff Bonwick wrote:
Not if the disk drive just *ignores* barrier and flush-cache commands and returns success. Some consumer drives really do exactly that. That's the issue that people are asking ZFS to work around.
Can someone please name a specific device (vendor + model + firmware revision) that does this? I see this claim thrown around like fact repeatedly, and yet I've never personally experienced an actual "consumer" device that discarded FLUSH CACHE (EXT) before, and nobody I know can name one that did. The only exceptions that might "appear" to be ignoring a barrier that I've witnessed are "high fly" writes in rotating drives, where the servo system couldn't detect that the head struck a defect and was deflected too high to write, and devices that don't support the command at all (and thus abort 51/04 attempts to flush the cache). BTW, funky/busted bridge hardware in external USB devices don't count. I'm more interested in major rotating drive vendors... Seagate/Maxtor, WD, Hitachi/IBM, Fujitsu, Toshiba, etc. --eric -- Eric D. Mudama edmud...@mail.bounceswoosh.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
