> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Nicolas Williams > > > I recently got a new SSD (ocz vertex LE 50gb) > > > > It seems to work really well as a ZIL performance wise. > > I know it doesn't have a supercap so lets' say dataloss > > occurs....is it just dataloss or is it pool loss? > > Just dataloss.
WRONG! The correct answer depends on your version of solaris/opensolaris. More specifically, it depends on the zpool version. The latest fully updated sol10 and the latest opensolaris release (2009.06) only go up to zpool 14 or 15. But in zpool 19 is when a ZIL loss doesn't permanently offline the whole pool. I know this is available in the developer builds. The best answer to this, I think, is in the ZFS Best Practices Guide: (uggh, it's down right now, so I can't paste the link) If you have zpool <19, and you lose an unmirrored ZIL, then you lose your pool. Also, as a configurable option apparently, I know on my systems, it also meant I needed to power cycle. If you have zpool >=19, and you lose an unmirrored ZIL, then performance will be degraded, but everything continues to work as normal. Apparently the most common mode of failure for SSD's is also failure to read. To make it worse, a ZIL is only read after system crash, which means the possibility of having a failed SSD undetected must be taken into consideration. If you do discover a failed ZIL after crash, with zpool <19 your pool is lost. But with zpool >=19 only the unplayed writes are lost. With zpool >=19, your pool will be intact, but you would lose up to 30sec of writes that occurred just before the crash. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
