1. A data storage system configured as a node in a distributed data store, the data storage system comprising: an RDMA-enabled network adapter configured to communicate with one or more other data storage systems in the distributed data store; and a role management unit configured to: detect a node identification number associated with each of the one or more other data storage systems, compare a node identification number assigned to the data storage system with each of the detected node identification numbers to generate comparison results, determine whether the data storage system is to perform either a server role or a client role with respect to each of the one or more other data storage systems on the basis of the comparison results, and set up the network adapter to operate in both an RDMA server mode and an RDMA client mode in the same time period during runtime according to the determined roles, wherein in response to the determining and the setting up by the role management unit, the RDMA-enabled network adapter is configured to: initiate an RDMA reliable connection to establish a duplex communication channel with a first one of the one or more other data storage systems in response to the data storage system being determined to perform a client role with respect to the first one of the one or more other data storage systems; and in the same time period as the data storage system being determined to perform the client role, listen for incoming RDMA connections from a second one of the one or more other data storage systems in response to the data storage system being determined to perform a server role with respect to the second one of the one or more other data storage systems.