Updates to README to document the NODES configuration variable.

Also add table of contents to README to encourage readers to look at
the "configuration" section.

Signed-off-by: Martin Schwenke <martin@meltin.net>

1 files changed, 42 insertions, 0 deletions

diff --git a/README b/README
index 47379c2..2f59b36 100644
--- a/README
+++ b/README
@@ -5,6 +5,15 @@ Autocluster is set of scripts for building virtual clusters to test
 clustered Samba.  It uses Linux's libvirt and KVM virtualisation
 engine.
 
+CONTENTS
+========
+
+* Basic Setup
+
+* Configuration
+
+* Development Hints
+
 BASIC SETUP
 ===========
 
@@ -239,6 +248,39 @@ CONFIGURATION
   definition - the most obvious one is the (rarely used) RHEL_ARCH
   option, which is used in the default ISO setting for each release.
 
+* The NODES configuration variable control the types of nodes that are
+  created.  At the time of writing, the default value is:
+
+    NODES="rhel_base:0-3"
+
+  This means that you get 4 nodes, at IP offsets 0, 1, 2, & 3 from
+  FIRSTIP, all part of the CTDB cluster.  That is, with standard
+  settings and FIRSTIP=35, 4 nodes will be created in the IP range
+  10.0.0.35 to 10.0.0.38.
+
+  The SoFS releases use a default of:
+
+    NODES="tsm_server:0 sofs_gui:1 sofs_front:2-4"
+
+  which should produce a set of nodes the same as the previous SoFS
+  default.  You can add extra rhel_base nodes if you need them for
+  test clients or some other purpose:
+
+    NODES="$NODES rhel_base:7,8"
+
+  This produces an additional 2 base RHEL nodes at IP offsets 7 & 8
+  from FIRSTIP.  Since sofs_* nodes are present, these base nodes will
+  not be part of the CTDB cluster - they're just extra.
+
+  For many standard use cases the nodes specified by NODES can be
+  modified by setting NUMNODES, WITH_SOFS_GUI and WITH_TSM_NODE.
+  However, these options can't be used to create nodes without
+  specifying IP offsets - except WITH_TSM_NODE, which checks to see if
+  IP offset 0 is vacant.  Therefore, for many uses you can ignore the
+  NODES variable.  However, NODES is very useful for specifying
+  alternative mixes of node types, especially with the addition of new
+  node types.
+
 DEVELOPMENT HINTS
 =================