On Nov 1, 2010, at 5:09 PM, Ian D <rewar...@hotmail.com> wrote: >> Maybe you are experiencing this: >> http://opensolaris.org/jive/thread.jspa?threadID=11942 > > It does look like this... Is this really the expected behaviour? That's just > unacceptable. It is so bad it sometimes drop connection and fail copies and > SQL queries...
Then set the zfs_write_limit_override to a reasonable value. Depending on the speed of your ZIL and/or backing store (for async IO) you will need to limit the write size in such a way so TXG1 is fully committed before TXG2 fills. Myself, with a RAID controller with a 512MB BBU write-back cache I set the write limit to 512MB which allows my setup to commit-before-fill. It also prevents ARC from discarding good read cache data in favor of write cache. Others may have a good calculation based on ARC execution plan timings, disk seek and sustained throughput to give an accurate figure based on one's setup, otherwise start with a reasonable value, say 1GB, and decrease until the pauses stop. -Ross _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
