Check here: http://cvs.opensolaris.org/source/xref/on/usr/src/uts/common/fs/zfs/vdev_disk.c#157
-r Phil Brown writes: > Roch Bourbonnais - Performance Engineering wrote: > > I'm puzzled by 2 things. > > > > Naively I'd think a write_cache should not help throughput > > test since the cache should fill up after which you should still be > > throttled by the physical drain rate. You clearly show that > > it helps; Anyone knows why/how a cache helps throughput ? > > > > And the second thing...quick search, this seems relevant > > > > Bug ID: 6397876 > > Synopsis: sata drives need default write cache controlled via property > > Integrated in Build: snv_38 > > http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6397876 > > > > > well, that just says that the cache settings dont stick across reboot. that > doesnt seem to have any bearing on whether zfs toggles write cache or not. > > From the sound of things, it sounds like what was previously written on > this list was incorrect: I now infer that zfs does NOT do any "smart > toggling" of write cache enable/disable on drives that it uses. > (although it may or may not do some "flush cache" calls at appropriate > moments) > > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
