improve introduction

Provided by David Noveck with small edits from me.

diff --git a/scsi_nvme_middle.xml b/scsi_nvme_middle.xml
index 62cc1d02dd680ffa235e73de04a34945d700fdcb..75d7369ae2b497487ea0308e80921504b077d23c 100644 (file)
--- a/scsi_nvme_middle.xml
+++ b/scsi_nvme_middle.xml
@@ -3,6 +3,20 @@
 <middle>
 
 <section anchor="sec:intro" title="Introduction">
+  <t>
+    NFSv4.1 (in <xref target="RFC8881" />) includes a pNFS feature that allows
+    reads and writes to be performed by other means than directing read and
+    write operations to the server.  Through use of this feature. The server,
+    in the role of metadata server is responsible for managing file and
+    directory metadata while separate means are provided for execution of
+    reads and writes.
+  </t>
+  <t>
+    These other means of performing file read and writes are defined  by
+    individual mapping types which often have their own specifications.  The
+    SCSI Layout Type, defined in RFC8154, describes how IO is to be done
+    directly to block storage devices.
+  </t>
   <t>
     The pNFS Small Computer System Interface (SCSI) layout
     <xref target="RFC8154" /> is a layout type
@@ -12,20 +26,19 @@
     devices.
   </t>
   <t>
-    This document explains how to access NVM Command set Namespaces
-    <xref target="NVME-NVM" /> exported by NVMe Controllers implementing
-    the NVMe Base specification (<xref target="NVME-BASE" />) using
-    the SCSI layout type.
-
-    This document works independent of the underlying transport used by
-    the NVMe Controller and thus supports Controllers implementing a
-    wide variety of transports, including PCIe Express, RDMA, TCP and
-    Fibre Channel.
+    This document defines how NVMe Namespaces using the NVM Command Set
+    <xref target="NVME-NVM" /> exported by NVMe Controllers implementing the
+    NVMe Base specification <xref target="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.
   </t>
   <t>
-    This document does not amend the pNFS SCSI layout document, but
-    instead explains how to map the SCSI constructs used in
-    the pNFS SCSI layout document to NVMe concepts.
+    This document does not amend the existing SCSI layout document.  Rather, it
+    defines how NVMe Namespaces can be used within the SCSI Layout by
+    establishing a mapping of the SCSI constructs used in the SCSI layout
+    document to corresponding NVMe constructs.
   </t>
 
   <section anchor="ssc:intro:reqlang" title="Requirements Language">