From 4e9509840f2f6d3867f3d71246010daf426d87b3 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 10 Oct 2023 11:40:19 +0200 Subject: [PATCH] add a quick blurb on nvme and why it matters to the introduction --- scsi-nvme.md | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/scsi-nvme.md b/scsi-nvme.md index 8e41f81..a8ab04a 100644 --- a/scsi-nvme.md +++ b/scsi-nvme.md @@ -94,6 +94,8 @@ This document specifies how to use the Parallel Network File System (pNFS) SCSI Layout Type to access storage devices using the NVMe protocol family. + + --- middle # Introduction {#sec:intro} @@ -106,15 +108,20 @@ directory metadata while separate means are provided for execution of reads and writes. These other means of performing file reads and writes are defined by -individual mapping types which often have their own specifications. The -SCSI Layout Type, defined in RFC8154, describes how I/O is to be done -directly to block storage devices. +individual mapping types which often have their own specifications. -The pNFS Small Computer System Interface (SCSI) layout {{RFC8154}} is a layout type -that allows NFS clients to directly perform I/O to block storage devices +The pNFS Small Computer System Interface (SCSI) layout {{RFC8154}} is a layout +type that allows NFS clients to directly perform I/O to block storage devices while bypassing the Metadata Server (MDS). It is specified by using -concepts from the SCSI protocol family for the data path to the storage -devices. +concepts from the SCSI protocol family for the data path to the storage devices. + +NVM Express (NVMe), or the Non-Volatile Memory Host Controller Interface +Specification, is a set of specifications to talk to storage devices over +a number of protocols such as PCI Express (PCIe), Fibre Channel (FC) and +TCP/IP or Remote Direct Memory Access (RDMA) networking. NVMe is currently +the by far dominant protocol used to access PCIe Solid State Disks (SSDs), +and increasingly adopted for remote storage access where it replaces +SCSI-based protocols such as iSCSI. This document defines how NVMe Namespaces using the NVM Command Set {{NVME-NVM}} exported by NVMe Controllers implementing the @@ -122,7 +129,7 @@ NVMe Base specification {{NVME-BASE}} are to be used as storage devices using the SCSI Layout Type. The definition is independent of the underlying transport used by the NVMe Controller and thus supports Controllers implementing a wide variety -of transports, including PCI Express, RDMA, TCP and FibreChannel. +of transports, including PCI Express, RDMA, TCP and Fibre Channel. This document does not amend the existing SCSI layout document. Rather, it -- 2.49.0