ZFS is an innovative file system invented by Sun, on which a user can construct mirror, single faulttolerant or double faulttolerant soft Raid systems. Its doubleerasure code is the ReedSolomon (RS) code. RS code based on calculating in the Galois field has a high time complexity. ZFS uses an appending writing strategy after the writing request aggregation instead of the traditional overwriting strategy. The performance of coding is one of the most important factors for ZFS, because coding calculation is necessary during every write operation. An approach to improving the writing performance by combining between ZFS and the RDP code whose computation is based on exclusiveor, instead of RS code, is shown. We have designed and implemented an algorithm by using cache’s feature to improve the RDP coding performance in ZFS. Finally, the experiments have validated this approach.