In the modern data centre, SSDs are increasingly used by enterprises to deliver much better speeds and response times than spinning drives. NVMe is a standardised protocol which was developed to enable non-volatile memories such as SSDs to leverage PCIe slots that connect directly to the CPU to achieve much faster data transfer rates and reduce latency. This results in significantly improved storage performance and removes the storage bottlenecks caused by legacy interfaces such as SAS and SATA.
However, in an enterprise setting, the bottleneck then moves to the network and scaling often becomes an issue. Storage Area Network (SAN), which is typically used to interconnect and present shared pools of storage devices to multiple servers, uses the antiquated SCSI protocol for communication. The problem is that without faster protocol technologies, enterprises still won’t be able to get the most out of their NVMe-enabled storage.
To overcome network limitations, a storage networking technology called NVMe Over Fabrics, or NVMe-oF, was developed to allow NVMe storage to be accessed remotely and share data at the speed of NVMe (or at least close to it).
NVMe-oF enables users to take full advantage of the performance of SSDs by allowing the network to use NVMe’s low-latency protocol instead of SCSI to deliver faster and more efficient connectivity between storage and servers as well as a reduction in CPU utilisation of application host servers.
This is made possible through the use of Remote Direct Memory Access (RDMA), which provides direct access from the memory of one computer to the memory of another with minimal CPU usage. Alternatively, it can also be delivered through a couple of other fabric implementations, such as fibre channel or TCP.
In practice, since NVMe-oF offers very low latency, from the user’s perspective, there will be very little difference between accessing local storage and remote storage.
In simple terms, NVMe is a communication transfer protocol developed for SSDs, while NVMe Over Fabrics is a storage networking protocol for NVMe-enabled storage arrays. NVMe-oF enables faster network to accommodate SSD’s blazing performance and fill the performance gap that existed between storage and storage network technologies.
