Abstract: To solve the problem that RAID5 performance ineffective for small writes, a new high performance read and write mechanism for redundancy data is brought up, which is called RMB.By Asynchronous Parity Calculating.the mechanism RMR optimized the write-update mechanism of tradition al RAID5 and decomposed the concentrated operations of calculating parity blocks into writing mirror and asynchronous calculating.The new algorithm accomplish the decomposition of the tight data, improve the concurrency state and decrease the count of calculate by the way of merge ring several versions.It shows from experiments that RMR will substantially improve the performance of small writes, the peak value will be over four times as before under the out-of-band mode.