Windows File Storage (SMB)

Accelerating Remote Storage Access - Breakthrough Performance, Scaling and Resiliency

The continued expansion of business-critical information and rich content within extended enterprises continues to change the storage dynamic in a wide range of industries and organizations. This market trend drives the need for higher connectivity speed and the adaptation of the clustering architecture. In order to address market needs Microsoft and Mellanox have joined together to provide a solution for remote storage access that allows faster and more efficient file servers for server applications, such as Hyper-V and SQL Server.

Implemented in Windows Server® 2012 R2: This solution enhanced the Server Message Block (SMB) protocol to leverage the capabilities of Mellanox's RDMA interconnect technologies in a way that provides greater performance, scale and reduced CPU utilization. These RDMA-based networking technologies include Mellanox's FDR 56Gb/s InfiniBand and 40Gb/s Ethernet with RoCE interconnect products.


Figure 1: Basic SMB Direct (SMB over RDMA) Architecture

Windows Server® 2012 R2 with SMB Direct

In Windows Server® 2012 R2, the SMB protocol for remote storage has been enhanced to allow faster and more efficient file servers for applications, such as Hyper-V and SQL Server. As part of the SMB protocol, two new features, SMB Direct and SMB Multichannel, enable customers to deploy storage for server applications on cost efficient, continuously available, high performance file servers.

SMB Direct supports the use of network adapters that have remote direct memory access (RDMA) capability. SMB Direct (SMB over RDMA) is a new storage protocol in Windows Server® 2012 R2 that includes:

  • Increased throughput: Leverages the full throughput of high speed networks in which the network adapters coordinate the transfer of large amounts of data at line speed.
  • Low latency: Provides extremely fast responses to network requests, and, as a result, makes remote file storage feel as if it is directly attached block storage.
  • Low CPU utilization: Uses fewer CPU cycles when transferring data over the network, which leaves more power available to server applications.

SMB Multichannel allows file servers to use multiple network connections simultaneously and includes the following capabilities:

  • Fault tolerance: When using multiple network connections at the same time, the file server continues functioning despite the loss of a network connection.
  • Increased throughput: The file server can simultaneously transmit more data using multiple connections for high speed network adapters or multiple network adapters.

Both SMB Direct and SMB Multichannel are automatically configured by Windows Server® 2012 R2.

Mellanox RDMA Based Interconnect Solution

Mellanox's end-to-end connectivity solutions enable the highest performance and most efficient data center infrastructure, and they support up to 40Gb/s Ethernet with RoCE or 56Gb/s InfiniBand servers and storage interconnect. Compared to traditional hardware and software architecture which imposes a significant load on a server's CPU and memory, Mellanox products use offloads like RDMA that accelerate I/O by allowing application software to bypass most layers of software and communicate directly with the hardware, enabling servers to place information directly into the memory of another computer. The technology reduces latency and maximizes the CPU overhead.


Figure 2: RDMA Operation Architecture

When an application performs an RDMA Read or Write request, no data copying is performed. The RDMA request is issued from an application running in user space to the local NIC and then carried over the network to the remote NIC without requiring any kernel involvement. Request completions might be processed either entirely in user space (by polling a user-level completion queue) or through the kernel in cases where the application wishes to sleep until a completion occurs.