> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Philippe Schwarz > > 3Ware cards > > Any drawback (except that without BBU, i've got a pb in case of power > loss) in enabling the WC with ZFS ?
If you don't have a BBU, and you care about your data, don't enable WriteBack. If you enable writeback without a BBU, you might as well just disable ZIL instead. It's more effective, and just as dangerous. Actually, disabling the ZIL is probably faster *and* safer than running WriteBack without BBU. But if you're impressed with performance by enabling writeback, you can still do better ... The most effective thing you could possibly do is to disable the writeback, and add SSD for log device. ZFS is able to perform in this configuration, better than the WriteBack. And in this situation, surprisingly, enabling the WriteBack actually hurts performance slightly. The performance of writeback vs naked disk is comparable to the performance of SSD log vs writeback. So prepare yourself to be impressed one more time. The performance with disabled ZIL is yet again, another impressive step. And this performance is unbeatable. There are situations when disabled ZIL is actually a good configuration. If you don't know ... I'll suggest posting again, to learn when it's appropriate to disable ZIL. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
