Dell Storage with Microsoft Storage Spaces Best Practices Guide

Remote Direct Memory Access (RDMA) allows for significantly increased throughput and low latency by performing direct memory transfers between servers.

For Scale-Out File Server configurations, SMB Direct is a feature of Windows Server 2012 R2 that enables the use of RDMA between SMB clients and the server. SMB Direct requires a network adapter, which supports the RDMA protocol. Also, both the storage nodes and the SMB clients must have RDMA adapters installed to use SMB Direct. For more information about a list of supported RDMA adapters, see the Dell Storage with Microsoft Storage Spaces Support Matrix available at Dell.com/dsmsmanuals.

Configure RDMA adapters on all SMB clients and servers for jumbo frames with the MTU frame size set to 9 KB. Also, verify that flow control is enabled on every NIC.

Also, when adding supported RDMA adapters to the solution there are several steps required in Windows Server 2012 R2 to ensure SMB Direct is enabled, existing SMB connections are refreshed, and SMB routing is configured (if supported by the adapter). For more information about configuring the RDMA adapters, see the Dell Storage with Microsoft Storage Spaces Deployment Guide available at Dell.com/ dsmsmanuals.

For Converged configurations, RDMA is typically used for internal communication between server cluster nodes with heavy I/O profiles such as CSV redirection and Hyper-V live Migration. RDMA adapters should not be teamed or added to a Hyper-V virtual switch, because they will lose the RDMA functionality. Configure RDMA adapters on all servers for jumbo frames with the MTU frame size set to 9 KB. Also, ensure that flow control is enabled on every NIC.