From 5078fb20754a5dc4d6bb1356cdca9512b7b43a65 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sun, 4 Nov 2007 21:40:02 +0000
Subject: [PATCH] Document possible problems with NFS tablespaces.

---
 doc/src/sgml/manage-ag.sgml | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/doc/src/sgml/manage-ag.sgml b/doc/src/sgml/manage-ag.sgml
index bc128ec3a7..4c54066734 100644
--- a/doc/src/sgml/manage-ag.sgml
+++ b/doc/src/sgml/manage-ag.sgml
@@ -495,5 +495,31 @@ SELECT spcname FROM pg_tablespace;
    the old tablespace locations.)
   </para> 
 
+  <sect2 id="manage-ag-tablespaces-nfs">
+   <title>Network File Systems</title>
+
+   <indexterm zone="manage-ag-tablespaces-nfs">
+    <primary>Network File Systems</primary>
+   </indexterm>
+   <indexterm><primary><acronym>NFS</></><see>Network File Systems</></>
+   <indexterm><primary>Network Attached Storage (<acronym>NAS</>)</><see>Network File Systems</></>
+
+   <para>
+    Many installations create tablespace on network file systems.
+    Sometimes this is done directly via <acronym>NFS</>, or by using a
+    Network Attached Storage (<acronym>NAS</>) device that uses
+    <acronym>NFS</> internally.  <productname>PostgreSQL</> does nothing
+    special for <acronym>NFS</> file systems, meaning it assumes
+    <acronym>NFS</> behaves exactly like locally-connected drives.  If
+    client and server <acronym>NFS</> implementations have non-standard
+    semantics, this can cause reliability problems (see <ulink
+    url="http://www.time-travellers.org/shane/papers/NFS_considered_harmful.html"></ulink>).
+    Specifically, delayed (asynchonous) writes to the <acronym>NFS</>
+    server can cause reliability problems;   if possible, mount
+    <acronym>NFS</> file systems synchonously to avoid this.
+   </para>
+
+  </sect2>
+
  </sect1>
 </chapter>
-- 
2.39.5