> Also, (Richard can address this better than I) you may want to disable > the ZIL or have your array ignore the write cache flushes that ZFS issues.
The latter is quite a reasonable thing to do, since the array has battery-backed cache. The ZIL should almost [b]never[/b] be disabled. The only reason I can think of is to determine whether a performance issue is caused by the ZIL. Disabling the ZIL does not only disable the intent log; it also causes ZFS to renege on the contract that fsync(), O_SYNC, and friends ensure that data is safely stored. A mail server, for instance, relies on this contract to ensure that a message is on disk before acknowledging its reception; if the ZIL is disabled, incoming messages can be lost in the event of a system crash. A database relies on this contract to ensure that its log is on disk before modifying its tables; if the ZIL is disabled, the database may be damaged and uncoverable in the event of a system crash. The ZIL is a necessary part of ZFS. Just because the ZFS file structure will be consistent after a system crash even with the ZIL disabled does not mean that disabling it is safe! This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
