Keep pool capacity below 90% for best performance
Mirrored pools are recommended over RAID-Z pools for random read/write workloads
Separate log devices
Recommended to improve synchronous write performance
With a high synchronous write load, prevents fragmentation of writing many log blocks in the main pool
Separate cache devices are recommended to improve read performance
Scrub/resilver - A very large RAID-Z pool with lots of devices will have longer scrub and resilver times
Pool performance is slow – Use the zpool status command to rule out any hardware problems that are causing pool performance problems. If no problems show up in the zpool status command, use the fmdump command to display hardware faults or use the fmdump –eV command to review any hardware errors that have not yet resulted in a reported fault.