Chapter 1. Red Hat High Availability Add-On Configuration and Management Overview

Red Hat High Availability Add-On allows you to connect a group of computers (called nodes or members) to work together as a cluster. You can use Red Hat High Availability Add-On to suit your clustering needs (for example, setting up a cluster for sharing files on a GFS2 file system or setting up service failover).

Note

For information on best practices for deploying and upgrading Red Hat Enterprise Linux clusters using the High Availability Add-On and Red Hat Global File System 2 (GFS2) refer to the article "Red Hat Enterprise Linux Cluster, High Availability, and GFS Deployment Best Practices" on Red Hat Customer Portal at https://access.redhat.com/site/articles/40051.
This chapter provides a summary of documentation features and updates that have been added to the Red Hat High Availability Add-On since the initial release of Red Hat Enterprise Linux 6, followed by an overview of configuring and managing the Red Hat High Availability Add-On.

1.1. New and Changed Features

This section lists new and changed features of the Red Hat High Availability Add-On documentation that have been added since the initial release of Red Hat Enterprise Linux 6.

1.1.1. New and Changed Features for Red Hat Enterprise Linux 6.1

Red Hat Enterprise Linux 6.1 includes the following documentation and feature updates and changes.
In addition, small corrections and clarifications have been made throughout the document.

1.1.2. New and Changed Features for Red Hat Enterprise Linux 6.2

Red Hat Enterprise Linux 6.2 includes the following documentation and feature updates and changes.
  • Red Hat Enterprise Linux now provides support for running Clustered Samba in an active/active configuration. For information on clustered Samba configuration, refer to Chapter 11, Clustered Samba Configuration.
  • Although any user able to authenticate on the system that is hosting luci can log in to luci, as of Red Hat Enterprise Linux 6.2 only the root user on the system that is running luci can access any of the luci components until an administrator (the root user or a user with administrator permission) sets permissions for that user. For information on setting luci permissions for users, refer to Section 3.3, “Controlling Access to luci”.
  • The nodes in a cluster can communicate with each other using the UDP unicast transport mechanism. For information on configuring UDP unicast, refer to Section 2.12, “UDP Unicast Traffic”.
  • You can now configure some aspects of luci's behavior by means of the /etc/sysconfig/luci file. For example, you can specifically configure the only IP address luci is being served at. For information on configuring the only IP address luci is being served at, refer to Table 2.2, “Enabled IP Port on a Computer That Runs luci. For information on the /etc/sysconfig/luci file in general, refer to Section 2.4, “Configuring luci with /etc/sysconfig/luci.
  • The ccs command now includes the --lsfenceopts option, which prints a list of available fence devices, and the --lsfenceopts fence_type option, which prints each available fence type. For information on these options, refer to Section 5.6, “Listing Fence Devices and Fence Device Options”.
  • The ccs command now includes the --lsserviceopts option, which prints a list of cluster services currently available for your cluster, and the --lsserviceopts service_type option, which prints a list of the options you can specify for a particular service type. For information on these options, refer to Section 5.11, “Listing Available Cluster Services and Resources”.
  • The Red Hat Enterprise Linux 6.2 release provides support for the VMware (SOAP Interface) fence agent. For information on fence device parameters, refer to Appendix A, Fence Device Parameters.
  • The Red Hat Enterprise Linux 6.2 release provides support for the RHEV-M REST API fence agent, against RHEV 3.0 and later. For information on fence device parameters, refer to Appendix A, Fence Device Parameters.
  • As of the Red Hat Enterprise Linux 6.2 release, when you configure a virtual machine in a cluster with the ccs command you can use the --addvm option (rather than the addservice option). This ensures that the vm resource is defined directly under the rm configuration node in the cluster configuration file. For information on configuring virtual machine resources with the ccs command, refer to Section 5.12, “Virtual Machine Resources”.
  • This document includes a new appendix, Appendix D, Cluster Service Resource Check and Failover Timeout. This appendix describes how rgmanager monitors the status of cluster resources, and how to modify the status check interval. The appendix also describes the __enforce_timeouts service parameter, which indicates that a timeout for an operation should cause a service to fail.
  • This document includes a new section, Section 2.3.3, “Configuring the iptables Firewall to Allow Cluster Components”. This section shows the filtering you can use to allow multicast traffic through the iptables firewall for the various cluster components.
In addition, small corrections and clarifications have been made throughout the document.

1.1.3. New and Changed Features for Red Hat Enterprise Linux 6.3

Red Hat Enterprise Linux 6.3 includes the following documentation and feature updates and changes.
In addition, small corrections and clarifications have been made throughout the document.

1.1.4. New and Changed Features for Red Hat Enterprise Linux 6.4

Red Hat Enterprise Linux 6.4 includes the following documentation and feature updates and changes.
In addition, small corrections and clarifications have been made throughout the document.

1.1.5. New and Changed Features for Red Hat Enterprise Linux 6.5

Red Hat Enterprise Linux 6.5 includes the following documentation and feature updates and changes.
In addition, many small corrections and clarifications have been made throughout the document.