Why use RDMA?

What is RDMA

• Remote
  data transfers between nodes in a network
• Direct
  no Operating System Kernel involvement in transfers –everything about a transfer offloaded onto Interface Card
• Memory
  transfers between user space application virtual memory –no extra copying or buffering
• Access
  send, receive, read, write, atomic operations

RDMA has those advantages than others:

• High throughput
• Low latency
• High messaging rate
• Low CPU utilization
• Low memory bus contention
• Message boundaries preserved
• Asynchronous operation
• Kernel-bypass, FlexSDS polling mode and kernel-bypass engine use all of up benefits.

Where using RDMA in FlexSDS:

• iSER (iSCSI extension for RDMA, iSCSI over RDMA)
• NVMe over Fabrics (RDMA)
• Replication between storage nodes