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<H2 align="center">Starting and testing CTDB</h2>

The CTDB log is in /var/log/log.ctdb so look in this file if something
did not start correctly.<p>

You can ensure that ctdb is running on all nodes using
<pre>
  onnode all service ctdb start
</pre>
Verify that the CTDB daemon started properly. There should normally be at least 2 processes started for CTDB, one for the main daemon and one for the recovery daemon.
<pre>
  onnode all pidof ctdbd
</pre>

Once all CTDB nodes have started, verify that they are correctly
talking to each other.<p>

There should be one TCP connection from the private ip address on each
node to TCP port 4379 on each of the other nodes in the cluster.
<pre>
  onnode all netstat -tn | grep 4379
</pre>


<h2>Automatically restarting CTDB</h2>

If you wish to cope with software faults in ctdb, or want ctdb to
automatically restart when an administration kills it, then you may
wish to add a cron entry for root like this:

<pre>
 * * * * * /etc/init.d/ctdb cron > /dev/null 2>&1
</pre>


<h2>Testing CTDB</h2>

Once your cluster is up and running, you may wish to know how to test that it is functioning correctly. The following tests may help with that

<h3>The ctdb tool</h3>

The ctdb package comes with a utility called ctdb that can be used to
view the behaviour of the ctdb cluster.<p>

If you run it with no options it will provide some terse usage information. The most commonly used commands are:
<pre>
 ctdb status
 ctdb ip
 ctdb ping
</pre>

<h3>ctdb status</h3>

The status command provides basic information about the cluster and the status of the nodes. when you run it you will get some output like:

<pre>
<strong>Number of nodes:4
vnn:0 10.1.1.1       OK (THIS NODE)
vnn:1 10.1.1.2       OK
vnn:2 10.1.1.3       OK
vnn:3 10.1.1.4       OK</strong>
Generation:1362079228
Size:4
hash:0 lmaster:0
hash:1 lmaster:1
hash:2 lmaster:2
hash:3 lmaster:3
<strong>Recovery mode:NORMAL (0)</strong>
Recovery master:0
</pre>

The important parts are in bold. This tells us that all 4 nodes are in
a healthy state.<p>

It also tells us that recovery mode is normal, which means that the
cluster has finished a recovery and is running in a normal fully
operational state.<p>

Recovery state will briefly change to "RECOVERY" when there ahs been a
node failure or something is wrong with the cluster.<p>

If the cluster remains in RECOVERY state for very long (many seconds)
there might be something wrong with the configuration. See
/var/log/log.ctdb.

<h3>ctdb ip</h3>

This command prints the current status of the public ip addresses and which physical node is currently serving that ip.

<pre>
Number of nodes:4
192.168.1.1         0
192.168.1.2         1
192.168.2.1         2
192.168.2.1         3
</pre>

<h3>ctdb ping</h3>
this command tries to "ping" each of the CTDB daemons in the cluster.
<pre>
  ctdb ping -n all

  response from 0 time=0.000050 sec  (13 clients)
  response from 1 time=0.000154 sec  (27 clients)
  response from 2 time=0.000114 sec  (17 clients)
  response from 3 time=0.000115 sec  (59 clients)
</pre>

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