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Applies to SUSE Linux Enterprise High Availability Extension 15 SP2

A Troubleshooting Edit source

Strange problems may occur that are not easy to understand, especially when starting to experiment with High Availability. However, there are several utilities that allow you to take a closer look at the High Availability internal processes. This chapter recommends various solutions.

A.1 Installation and First Steps Edit source

Troubleshooting difficulties when installing the packages or bringing the cluster online.

Are the HA packages installed?

The packages needed for configuring and managing a cluster are included in the High Availability installation pattern, available with the High Availability Extension.

Check if High Availability Extension is installed as an extension to SUSE Linux Enterprise Server 15 SP2 on each of the cluster nodes and if the High Availability pattern is installed on each of the machines as described in the Installation and Setup Quick Start.

Is the initial configuration the same for all cluster nodes?

To communicate with each other, all nodes belonging to the same cluster need to use the same bindnetaddr, mcastaddr and mcastport as described in Chapter 4, Using the YaST Cluster Module.

Check if the communication channels and options configured in /etc/corosync/corosync.conf are the same for all cluster nodes.

In case you use encrypted communication, check if the /etc/corosync/authkey file is available on all cluster nodes.

All corosync.conf settings except for nodeid must be the same; authkey files on all nodes must be identical.

Does the firewall allow communication via the mcastport?

If the mcastport used for communication between the cluster nodes is blocked by the firewall, the nodes cannot see each other. When doing the initial setup with YaST or the bootstrap scripts (as described in Chapter 4, Using the YaST Cluster Module or the Installation and Setup Quick Start, respectively), the firewall settings are usually automatically adjusted.

To make sure the mcastport is not blocked by the firewall, check the firewall settings on each node.

Are Pacemaker and Corosync started on each cluster node?

Usually, starting Pacemaker also starts the Corosync service. To check if both services are running:

root # crm cluster status

In case they are not running, start them by executing the following command:

root # crm cluster start

A.2 Logging Edit source

Where to find the log files?

Pacemaker writes its log files into the /var/log/pacemaker directory. The main Pacemaker log file is /var/log/pacemaker/pacemaker.log. In case you cannot find the log files, check the logging settings in /etc/sysconfig/pacemaker, Pacemaker's own configuration file. If PCMK_logfile is configured there, Pacemaker will use the path that is defined by this parameter.

If you need a cluster-wide report showing all relevant log files, see How can I create a report with an analysis of all my cluster nodes? for more information.

I enabled monitoring but there is no trace of monitoring operations in the log files?

The pacemaker-execd daemon does not log recurring monitor operations unless an error occurred. Logging all recurring operations would produce too much noise. Therefore recurring monitor operations are logged only once an hour.

I only get a failed message. Is it possible to get more information?

Add the --verbose parameter to your commands. If you do that multiple times, the debug output becomes quite verbose. See the logging data (sudo journalctl -n) for useful hints.

How can I get an overview of all my nodes and resources?

Use the crm_mon command. The following displays the resource operation history (option -o) and inactive resources (-r):

root # crm_mon -o -r

The display is refreshed when the status changes (to cancel this press CtrlC). An example may look like:

Example A.1: Stopped Resources
Last updated: Fri Aug 15 10:42:08 2014
Last change: Fri Aug 15 10:32:19 2014
 Stack: corosync
Current DC: bob (175704619) - partition with quorum
Version: 1.1.12-ad083a8
2 Nodes configured
3 Resources configured
       
Online: [ alice bob ]
       
Full list of resources:
       
my_ipaddress    (ocf:heartbeat:Dummy): Started bob
my_filesystem   (ocf:heartbeat:Dummy): Stopped
my_webserver    (ocf:heartbeat:Dummy): Stopped
       
Operations:
* Node bob: 
    my_ipaddress: migration-threshold=3
      + (14) start: rc=0 (ok)
      + (15) monitor: interval=10000ms rc=0 (ok)
      * Node alice:

The Pacemaker Explained PDF, available at http://www.clusterlabs.org/pacemaker/doc/, covers three different recovery types in the How are OCF Return Codes Interpreted? section.

How to view logs?

For a more detailed view of what is happening in your cluster, use the following command:

root # crm history log [NODE]

Replace NODE with the node you want to examine, or leave it empty. See Section A.5, “History” for further information.

A.3 Resources Edit source

How can I clean up my resources?

Use the following commands:

root # crm resource list
crm resource cleanup rscid [node]

If you leave out the node, the resource is cleaned on all nodes. More information can be found in Section 8.4.4, “Cleaning Up Resources”.

How can I list my currently known resources?

Use the command crm resource list to display your current resources.

I configured a resource, but it always fails. Why?

To check an OCF script use ocf-tester, for instance:

ocf-tester -n ip1 -o ip=YOUR_IP_ADDRESS \
  /usr/lib/ocf/resource.d/heartbeat/IPaddr

Use -o multiple times for more parameters. The list of required and optional parameters can be obtained by running crm ra info AGENT, for example:

root # crm ra info ocf:heartbeat:IPaddr

Before running ocf-tester, make sure the resource is not managed by the cluster.

Why do resources not fail over and why are there no errors?

The terminated node might be considered unclean. Then it is necessary to fence it. If the STONITH resource is not operational or does not exist, the remaining node will waiting for the fencing to happen. The fencing timeouts are typically high, so it may take quite a while to see any obvious sign of problems (if ever).

Yet another possible explanation is that a resource is simply not allowed to run on this node. That may be because of a failure which happened in the past and which was not cleaned. Or it may be because of an earlier administrative action, that is a location constraint with a negative score. Such a location constraint is inserted by the crm resource migrate command, for example.

Why can I never tell where my resource will run?

If there are no location constraints for a resource, its placement is subject to an (almost) random node choice. You are well advised to always express a preferred node for resources. That does not mean that you need to specify location preferences for all resources. One preference suffices for a set of related (colocated) resources. A node preference looks like this:

location rsc-prefers-alice rsc 100: alice

A.4 STONITH and Fencing Edit source

Why does my STONITH resource not start?

Start (or enable) operation includes checking the status of the device. If the device is not ready, the STONITH resource will fail to start.

At the same time the STONITH plugin will be asked to produce a host list. If this list is empty, there is no point in running a STONITH resource which cannot shoot anything. The name of the host on which STONITH is running is filtered from the list, since the node cannot shoot itself.

If you want to use single-host management devices such as lights-out devices, make sure that the STONITH resource is not allowed to run on the node which it is supposed to fence. Use an infinitely negative location node preference (constraint). The cluster will move the STONITH resource to another place where it can start, but not before informing you.

Why does fencing not happen, although I have the STONITH resource?

Each STONITH resource must provide a host list. This list may be inserted by hand in the STONITH resource configuration or retrieved from the device itself from outlet names, for example. That depends on the nature of the STONITH plugin. pacemaker-fenced uses the list to find out which STONITH resource can fence the target node. Only if the node appears in the list can the STONITH resource shoot (fence) the node.

If pacemaker-fenced does not find the node in any of the host lists provided by running STONITH resources, it will ask pacemaker-fenced instances on other nodes. If the target node does not show up in the host lists of other pacemaker-fenced instances, the fencing request ends in a timeout at the originating node.

Why does my STONITH resource fail occasionally?

Power management devices may give up if there is too much broadcast traffic. Space out the monitor operations. Given that fencing is necessary only once in a while (and hopefully never), checking the device status once a few hours is more than enough.

Also, some of these devices may refuse to talk to more than one party at the same time. This may be a problem if you keep a terminal or browser session open while the cluster tries to test the status.

A.5 History Edit source

How to retrieve status information or a log from a failed resource?

Use the history command and its subcommand resource:

root # crm history resource NAME1

This gives you a full transition log for the given resource only. However, it is possible to investigate more than one resource. Append the resource names after the first.

If you followed some naming conventions (see section ), the resource command makes it easier to investigate a group of resources. For example, this command investigates all primitives starting with db:

root # crm history resource db*

View the log file in /var/cache/crm/history/live/alice/ha-log.txt.

How can I reduce the history output?

There are two options for the history command:

  • Use exclude

  • Use timeframe

The exclude command let you set an additive regular expression that excludes certain patterns from the log. For example, the following command excludes all SSH, systemd, and kernel messages:

root # crm history exclude ssh|systemd|kernel.

With the timeframe command you limit the output to a certain range. For example, the following command shows all the events on August 23rd from 12:00 to 12:30:

root # crm history timeframe "Aug 23 12:00" "Aug 23 12:30"
How can I store a session for later inspection?

When you encounter a bug or an event that needs further examination, it is useful to store all the current settings. This file can be sent to support or viewed with bzless. For example:

crm(live)history# timeframe "Oct 13 15:00" "Oct 13 16:00"
crm(live)history# session save tux-test
crm(live)history# session pack
Report saved in '/root/tux-test.tar.bz2'

A.6 Hawk2 Edit source

Replacing the Self-Signed Certificate

To avoid the warning about the self-signed certificate on first Hawk2 start-up, replace the automatically created certificate with your own certificate (or a certificate that was signed by an official Certificate Authority, CA):

  1. Replace /etc/hawk/hawk.key with the private key.

  2. Replace /etc/hawk/hawk.pem with the certificate that Hawk2 should present.

  3. Restart the Hawk2 services to reload the new certificate:

    root # systemctl restart hawk-backend hawk

Change ownership of the files to root:haclient and make the files accessible to the group:

chown root:haclient /etc/hawk/hawk.key /etc/hawk/hawk.pem
chmod 640 /etc/hawk/hawk.key /etc/hawk/hawk.pem

A.7 Miscellaneous Edit source

How can I run commands on all cluster nodes?

Use the command pssh for this task. If necessary, install pssh. Create a file (for example hosts.txt) where you collect all your IP addresses or host names you want to visit. Make sure you can log in with ssh to each host listed in your hosts.txt file. If everything is correctly prepared, execute pssh and use the hosts.txt file (option -h) and the interactive mode (option -i) as shown in this example:

pssh -i -h hosts.txt "ls -l /corosync/*.conf"
[1] 08:28:32 [SUCCESS] root@venus.example.com
-rw-r--r-- 1 root root 1480 Nov 14 13:37 /etc/corosync/corosync.conf
[2] 08:28:32 [SUCCESS] root@192.168.2.102
-rw-r--r-- 1 root root 1480 Nov 14 13:37 /etc/corosync/corosync.conf
What is the state of my cluster?

To check the current state of your cluster, use one of the programs crm_mon or crm status. This displays the current DC and all the nodes and resources known by the current node.

Why can several nodes of my cluster not see each other?

There could be several reasons:

  • Look first in the configuration file /etc/corosync/corosync.conf. Check if the multicast or unicast address is the same for every node in the cluster (look in the interface section with the key mcastaddr).

  • Check your firewall settings.

  • Check if your switch supports multicast or unicast addresses.

  • Check if the connection between your nodes is broken. Most often, this is the result of a badly configured firewall. This also may be the reason for a split brain condition, where the cluster is partitioned.

Why can an OCFS2 device not be mounted?

Check the log messages (sudo journalctl -n) for the following line:

Jan 12 09:58:55 alice pacemaker-execd: [3487]: info: RA output: [...]
  ERROR: Could not load ocfs2_stackglue
Jan 12 16:04:22 alice modprobe: FATAL: Module ocfs2_stackglue not found.

In this case the Kernel module ocfs2_stackglue.ko is missing. Install the package ocfs2-kmp-default, ocfs2-kmp-pae or ocfs2-kmp-xen, depending on the installed Kernel.

How can I create a report with an analysis of all my cluster nodes?

On the crm shell, use crm report to create a report. This tool compiles:

  • Cluster-wide log files,

  • Package states,

  • DLM/OCFS2 states,

  • System information,

  • CIB history,

  • Parsing of core dump reports, if a debuginfo package is installed.

Usually run crm report with the following command:

root # crm report -f 0:00 -n alice -n bob

The command extracts all information since 0am on the hosts alice and bob and creates a *.tar.bz2 archive named crm_report-DATE.tar.bz2 in the current directory, for example, crm_report-Wed-03-Mar-2012. If you are only interested in a specific time frame, add the end time with the -t option.

Warning
Warning: Remove Sensitive Information

The crm report tool tries to remove any sensitive information from the CIB and the PE input files, however, it cannot know everything. If you have more sensitive information, supply additional patterns with the -p option (see man page). The log files and the crm_mon, ccm_tool, and crm_verify output are not sanitized.

Before sharing your data in any way, check the archive and remove all information you do not want to expose.

Customize the command execution with further options. For example, if you have a Pacemaker cluster, you certainly want to add the option -A. In case you have another user who has permissions to the cluster, use the -u option and specify this user (in addition to root and hacluster). In case you have a non-standard SSH port, use the -X option to add the port (for example, with the port 3479, use -X "-p 3479"). Further options can be found in the man page of crm report.

After crm report has analyzed all the relevant log files and created the directory (or archive), check the log files for an uppercase ERROR string. The most important files in the top level directory of the report are:

analysis.txt

Compares files that should be identical on all nodes.

corosync.txt

Contains a copy of the Corosync configuration file.

crm_mon.txt

Contains the output of the crm_mon command.

description.txt

Contains all cluster package versions on your nodes. There is also the sysinfo.txt file which is node specific. It is linked to the top directory.

This file can be used as a template to describe the issue you encountered and post it to https://github.com/ClusterLabs/crmsh/issues.

members.txt

A list of all nodes

sysinfo.txt

Contains a list of all relevant package names and their versions. Additionally, there is also a list of configuration files which are different from the original RPM package.

Node-specific files are stored in a subdirectory named by the node's name. It contains a copy of the directory /etc of the respective node.

In case you need to simplify the arguments, set your default values in the configuration file /etc/crm/crm.conf, section report. Further information is written in the man page man 8 crmsh_hb_report.

A.8 For More Information Edit source

For additional information about high availability on Linux, including configuring cluster resources and managing and customizing a High Availability cluster, see http://clusterlabs.org/wiki/Documentation.

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