Installation guide

As of Red Hat Enterprise Linux 6.1, you can use the following command to verify that all of the
nodes specified in the host's cluster configuration file have the identical cluster configuration file:
ccs -h host --checkconf
For information on the ccs command, see Chapter 5, Configuring Red Hat High Availability Add-On
With the ccs Command and Chapter 6, Managing Red Hat High Availability Add-On With ccs.
Make sure that you have configured chkconfi g o n for cluster services in the node that is
attempting to join the cluster.
Ensure that no firewall rules are blocking the node from communicating with other nodes in the
cluster.
9.4 . Clust er Daemon crashes
RGManager has a watchdog process that reboots the host if the main rg manag er process fails
unexpectedly. This causes the cluster node to get fenced and rg manag er to recover the service on
another host. When the watchdog daemon detects that the main rg manag er process has crashed
then it will reboot the cluster node, and the active cluster nodes will detect that the cluster node has
left and evict it from the cluster.
The lower number process ID (PID ) is the watchdog process that takes action if its child (the process
with the higher PID number) crashes. Capturing the core of the process with the higher PID number
using g co re can aid in troubleshooting a crashed daemon.
Install the packages that are required to capture and view the core, and ensure that both the
rg manager and rg manager-d ebug i nfo are the same version or the captured application core
might be unusable.
$ yum -y --enablerepo=rhel-debuginfo install gdb rgmanager-debuginfo
9.4 .1. Capt uring t he rg manag er Core at Runtime
There are two rg manager processes that are running as it is started. You must capture the core for
the rg manager process with the higher PID.
The following is an example output from the ps command showing two processes for rg manager.
$ ps aux | grep rgmanager | grep -v grep
root 22482 0.0 0.5 23544 5136 ? S<Ls Dec01 0:00 rgmanager
root 22483 0.0 0.2 78372 2060 ? S<l Dec01 0:47 rgmanager
In the following example, the pi d o f program is used to automatically determine the higher-
numbered pid, which is the appropriate pid to create the core. The full command captures the
application core for the process 22483 which has the higher pid number.
$ gcore -o /tmp/rgmanager-$(date '+%F_%s').core $(pidof -s rgmanager)
9.4 .2. Capt uring t he Core When t he Daemon Crashes
Red Hat Ent erprise Linux 6 Clust er Administ rat ion
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