Hey Roch - > We do not retain 2 copies of the same data. > > If the DB cache is made large enough to consume most of memory, > the ZFS copy will quickly be evicted to stage other I/Os on > their way to the DB cache. > > What problem does that pose ?
Can't answer that question empirically, because we can't measure this, but I imagine there's some overhead to ZFS cache management in evicting and replacing blocks, and that overhead could be eliminated if ZFS could be told not to cache the blocks at all. Now, obviously, whether this overhead would be in the noise level, or something that actually hurts sustainable performance will depend on several things, but I can envision scenerios where it's overhead I'd rather avoid if I could. Thanks, /jim _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
