On Jan 14, 2010, at 10:58 AM, Jeffry Molanus wrote: > Hi all, > > Are there any recommendations regarding min IOPS the backing storage pool > needs to have when flushing the SSD ZIL to the pool?
Pedantically, as many as you can afford :-) The DDRdrive folks sell IOPS at 200 IOPS/$. Sometimes people get confused about the ZIL and separate logs. For sizing purposes, the ZIL is a write-only workload. Data which is written to the ZIL is later asynchronously written to the pool when the txg is committed. > Consider a pool of 3x 2TB SATA disks in RAIZ1, you would roughly have 80 > IOPS. Any info about the relation between ZIL <> pool performance? Or will > the ZIL simply fill up and performance drops to pool speed? The ZFS write performance for this configuration should consistently be greater than 80 IOPS. We've seen measurements in the 600 write IOPS range. Why? Because ZFS writes tend to be contiguous. Also, with the SATA disk write cache enabled, bursts of writes are handled quite nicely. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
