Research On Replica Consistency Based On Ceph Distribute Storage System

In the environment of cloud based service, distributed storage system as the underlying storage is paid attention, due to its large capacity and high scalability. To solve the replica consistency problem, different distribute storage system used different strategy, include primary-copy, primary-chain, Paxos and NWR replica strategy. The single replica strategy can not adapt to the complex application environment.Ceph's strong consistent strategy has high aesthetic requirements for write operation. Write operation has to write every replica, so this strategy has high latency. To adapt to the complex application environment, designed a dynamic replica strategy based on the proportion of reading and writing. Based on the current number of read and write operations in the system, the system is divided into four kinds of state: reading-writing osteoporosis, reading intensive, writing intensive, reading-writing intensive. In different state, used different algorithm. The number of synchronous replicas is calculated by the proportion of reading and writing. And the other replica is asynchronous updated.According to the designed scheme, modify replica strategy of Ceph, and test on the modified system. The test results show that, the writing latency has reduced by 30%, and it is changed with the proportion of writing. This strategy basically achieved the designed goals.