Document possible problems with NFS tablespaces.

diff --git a/doc/src/sgml/manage-ag.sgml b/doc/src/sgml/manage-ag.sgml
index 691394223cf165753f7c9abf71874604f7b6c184..49566d10a310b8e9167fde79d6cd49331c018cb4 100644 (file)
--- a/doc/src/sgml/manage-ag.sgml
+++ b/doc/src/sgml/manage-ag.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  Managing Databases
@@ -495,5 +495,31 @@ SELECT spcname FROM pg_tablespace;
    the old tablespace locations.)
    
 
+  
+   Network File Systems
+
+   
+    Network File Systems
+   
+   NFSNetwork File Systems
+   Network Attached Storage (NAS)Network File Systems
+
+   
+    Many installations create tablespace on network file systems.
+    Sometimes this is done directly via NFS, or by using a
+    Network Attached Storage (NAS) device that uses
+    NFS internally.  PostgreSQL does nothing
+    special for NFS file systems, meaning it assumes
+    NFS behaves exactly like locally-connected drives.  If
+    client and server NFS implementations have non-standard
+    semantics, this can cause reliability problems (see 
+    url="http://www.time-travellers.org/shane/papers/NFS_considered_harmful.html">).
+    Specifically, delayed (asynchonous) writes to the NFS
+    server can cause reliability problems;   if possible, mount
+    NFS file systems synchonously to avoid this.
+   
+
+  
+