Assign data to physical drives to evenly balance the I/O load among the available disk drives.
Identify the most frequently accessed data, and increase access bandwidth to that data with mirroring or striping.
Both striped metadevices and RAID5 metadevices distribute data across multiple disk drives and help balance the I/O load. In addition, mirroring can also be used to help balance the I/O load.
Use DiskSuite Tool performance monitoring capabilities, and generic OS tools such as iostat(1M), to identify the most frequently accessed data. Once identified, the "access bandwidth" to this data can be increased using mirroring, striping, or RAID5.