Add mention that Shared Disk Failover can use file system mirroring of

the mirroring is consistent.

doc/src/sgml/high-availability.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.2 2006/11/20 15:07:13 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.3 2006/11/20 21:26:22 momjian Exp $ -->
 
 <chapter id="high-availability">
  <title>High Availability and Load Balancing</title>
@@ -98,7 +98,10 @@
     disk array fails or becomes corrupt, the primary and standby
     servers are both nonfunctional.  Another issue is that the
     standby server should never access the shared storage while
-    the primary server is running.
+    the primary server is running.  It is also possible to use
+    some type of file system mirroring to keep the standby server
+    current, but the mirroring must be done in a way that the
+    standby server has a consistent copy of the file system.
    </para>
   </listitem>
  </varlistentry>