Abstract: A data access method for making an asynchronous request to a block device is adapted to access a block device in a server end and perform corresponding processing according to a plurality of data access requests. The data access method includes the steps. A current request is received from a client. A virtual device of the block device is invoked. The current request is compared with a request queue storing a plurality of requests to be processed. The requests to be processed are selected from the request queue according to an access address of the current request. A request merging program is performed on the requests to be processed with adjacent access addresses and the current request to generate a merged request. The merged request is submitted to the request queue. The requests having low access capacities is merged, so as to improve the access efficiency of the block device.

Abstract: A system and a method of processing sender requests for remote replication are applied in local system having a plurality of network block devices (NBD). A fixed number of sender threads are created in local system to form sender thread pool. All NBDs receiving write request for corresponding remote mirror volume are serially connected to be circular linked list. A pointer is set to sequentially record latest processed NBD in circular linked list, the sender threads in the sender thread pool are allocated to actively search NBD to be processed pointed by the pointer according to a sequence in circular linked list, and processing of NBD pointed by the pointer is locked by using the sender thread, hence processing the sender request of NBD. Each time when the sender request is finished, the pointer is sequentially moved to next NBD and the sender request of corresponding NBD is performed.