Advantages
One Write or two Reads possible per mirrored pair
100% redundancy of data means no rebuild is necessary in case of a disk failure, just a copy to the replacement disk
Simplest RAID storage subsystem design

Disadvantages
Highest disk overhead of all RAID types (100%) - inefficient
Typically the RAID function is done by system software, loading the CPU/Server and possibly degrading throughput at high activity levels. Hardware implementation is strongly recommended

RAID 1

Mirroring and Duplexing