User manual NOVELL LINUX ENTERPRISE 11 HIGH AVAILABILITY

[. . . ] SUSE Linux Enterprise High Availability Extension 11 February 18, 2010 www. novell. com High Availability Guide High Availability Guide Copyright © 2006- 2010 Novell, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. 2 or (at your option) version 1. 3; with the Invariant Section being this copyright notice and license. A copy of the license version 1. 2 is included in the section entitled "GNU Free Documentation License". SUSE®, openSUSE®, the openSUSE® logo, Novell®, the Novell® logo, the N® logo, are registered trademarks of Novell, Inc. [. . . ] Review the output to make sure you know the source and cause of any errors. 3 If there are errors in the drbd. conf file, correct them before continuing. 4 If the partitions and settings are correct, run drbdadm again without the -d option. drbdadm adjust r0 This applies the configuration file to the DRBD resource. 14. 4. 2 Hostnames For DRBD, hostnames are case sensitive (Node0 would be a different host than node0). If you have several network devices and want to use a dedicated network device, the hostname will likely not resolve to the used ip address. In this case, use the parameter disable-ip-verification. Distributed Replicated Block Device (DRBD) 127 14. 4. 3 TCP Port 7788 If your system is unable to connect to the peer, this might be a problem with your local firewall. By default, DRBD uses the TCP port 7788 to access the other node. Make sure that this port is accessible on both nodes. 14. 4. 4 DRBD Devices Broken after Reboot In cases when DRBD does not know which of the real devices holds the latest data, it changes to a split brain condition. In this case, the respective DRBD subsystems come up as secondary and do not connect to each other. In this case, the following message is written to /var/log/messages: Split-Brain detected, dropping connection! To resolve this situation, enter the following on the node which has data to be discarded: drbdadm secondary r0 drbdadm -- --discard-my-data connect r0 On the node which has the latest data enter the following: drbdadm connect r0 14. 5 Additional Information The following open source resources are available for DRBD: · The following man pages for DRBD are available in the distribution: drbd(8) drbddisk(8) drbdsetup(8) drbdadm(8) drbd. conf(5) · Find a commented example configuration for DRBD at /usr/share/doc/ packages/drbd/drbd. conf 128 High Availability Guide · The project home page http://www. drbd. org. · http://clusterlabs. org/wiki/DRBD_HowTo_1. 0 by the Linux Pacemaker Cluster Stack Project. Distributed Replicated Block Device (DRBD) 129 Part IV. Troubleshooting and Reference Troubleshooting 15 Often, strange problems may occur that are not easy to understand (especially when starting to experiment with Heartbeat). However, there are several utilities that may be used to take a closer look at the Heartbeat internal processes. This chapter recommends various solutions. 15. 1 Installation Problems Troubleshooting difficulties installing the packages or in bringing the cluster online. . 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 add-on to SUSE Linux Enterprise Server 11 on each of the cluster nodes and if the High Availability pattern is installed on each of the machines as described in Section 3. 1, "Installing the High Availability Extension" (page 23). Is the initial configuration the same for all cluster nodes?In order to communicate with each other, all nodes belonging to the same cluster need to use the same bindnetaddr, mcastaddr and mcastport as described in Section 3. 2, "Initial Cluster Setup" (page 24). Troubleshooting 133 Check if the communication channels and options configured in /etc/ais/ openais. conf are the same for all cluster nodes. In case you use encrypted communication, check if the /etc/ais/authkey file is available on all cluster nodes. 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 configuring the initial setup with YaST as described in Section 3. 1, "Installing the High Availability Extension" (page 23), the firewall settings are usually automatically adjusted. To make sure the mcastport is not blocked by the firewall, check the settings in /etc/sysconfig/SuSEfirewall2 on each node. [. . . ] Find more information about LSB resource agents and the actual specification at http://www. linux-ha. org/LSBResourceAgent and http://www. linux-foundation. org/spec/refspecs/LSB_3. 0 . 0/LSB-Core-generic/LSB-Core-generic/iniscrptact. html node Any computer (real or virtual) that is a member of a cluster and invisible to the user. It continuously contacts one or more servers outside the cluster with ICMP pings. policy engine (PE) The policy engine computes the actions that need to be taken to implement policy changes in the CIB. This information is then passed on to the transaction engine, which in turn implements the policy changes in the cluster setup. [. . . ]