Mirroring stores multiple copies of data on a system. When you apply mirroring properly, data is continuously available. Mirroring also protects against data loss due to physical media failure. If the system crashes or a disk or other hardware fails, mirroring improves the chance of data recovery.

In some cases, you can also use mirroring to improve I/O performance. Unlike striping, the performance gain depends on the ratio of reads to writes in the disk accesses. If the system workload is primarily write-intensive (for example, greater than 30 percent writes), mirroring can reduce performance.