There are three types of codes for tolerating double disk failures in RAID（Redundant Arrays of Independent Disks） architectures: two dimension （2D） parity codes

Reed-Solomon（RS） codes and EVENODD codes.The complexity of encoding and decoding and the small write performance of the three types of codes are compared and analyzed. It is pointed out that the encoding of 2D codes is the simplest of the three

but the performance/price is lowest. Both RS and EVENODD codes require an optimal number of redundant disks

namely two.The RS codes are more complex than EVENODD

but the small write performance of RS is better than that of EVENODD.