Performance of RDMA-Capable Storage Protocols on Wide-Area Network
Source: Oak Ridge National Laboratory
Because of its high throughput, low CPU utilization, and direct data placement, RDMA (Remote Direct Memory Access) has been adopted for transport in a number of storage protocols, such as NFS and iSCSI. In this presentation, the author provides a performance evaluation of RDMA-based NFS and iSCSI on Wide-Area Network (WAN). The paper shows that these protocols, though benefit from RDMA on Local Area Network (LAN) and on WAN of short distance, are faced with a number of challenges to achieve good performance on long distance WAN. This is because of the low performance of RDMA reads on WAN, the small 4KB chunks used in NFS over RDMA, and the lack of RDMA capability in handling discontiguous data.