> 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.
Right; the tgx needs time to transfer the ZIL. > 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 Is there a method to determine this value before pool configuration ? Some sort of rule of thumb? It would be sad when you configure the pool and have to reconfigure later one because you discover the pool can't handle the tgx commits from SSD to disk fast enough. In other words; with Y as expected load you would require a minimal of X mirror devs or X raid-z vdevs in order to have a pool with enough bandwith/IO to flush the ZIL without stalling the system. Jeffry _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
