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Chapter 6. Clustering

New SNMP agent to query a Pacemaker cluster

The new pcs_snmp_agent agent allows you to query a Pacemaker cluster for data by means of SNMP. This agent provides basic information about a cluster, its nodes, and its resources. For information on configuring this agent, see the pcs_snmp_agent(8) man page and the High Availability Add-On Reference. (BZ#1367808)

Support for Red Hat Enterprise Linux High Availability clusters on Amazon Web Services

Red Hat Enterprise Linux 7.5 supports High Availability clusters of virtual machines (VMs) on Amazon Web Services (AWS). For information on configuring a Red Hat Enterprise Linux High Availability Cluster on AWS, see https://access.redhat.com/articles/3354781. (BZ#1451776)

Support for Red Hat Enterprise Linux High Availability clusters on Microsoft Azure

Red Hat Enterprise Linux 7.5 supports High Availability clusters of virtual machines (VMs) in Microsoft Azure. For information on configuring a Red Hat Enterprise Linux High Availability cluster on Microsoft Azure, see https://access.redhat.com/articles/3252491. (BZ#1476009)

Unfencing is done in resource cleanup only if relevant parameters changed

Previously, in a cluster that included a fence device that supports unfencing, such as fence_scsi or fence_mpath, a general resource cleanup or a cleanup of any stonith resource would always result in unfencing, including a restart of all resources. Now, unfencing is only done if the parameters to the device that supports unfencing changed. (BZ#1427648)

The pcsd port is now configurable

The port on which pcsd is listening can now be changed in the pcsd configuration file, and pcs can now communicate with pcsd using a custom port. This feature is primarily for the use of pcsd inside containers. (BZ#1415197)

Fencing and resource agents are now supported by AWS Python libraries and a CLI client

With this enhancement, Amazon Web Services Python libraries (python-boto3, python-botocore, and python-s3transfer) and a CLI client (awscli) have been added to support fencing and resource agents in high availability setups. (BZ#1512020)

Fencing in HA setups is now supported by Azure Python libraries

With this enhancement, Azure Python libraries (python-isodate, python-jwt, python-adal, python-msrest, python-msrestazure, and python-azure-sdk) have been added to support fencing in high availability setups. (BZ#1512021)

New features added to the sbd binary.

The sbd binary used as a command line tool now provides the following additional features:
  • Easy verification of the functionality of a watchdog device
  • Ability to query a list of available watchdog devices
For information on the sbd command line tool, see the sbd(8) man page. (BZ#1462002)

sbd rebased to version 1.3.1

The sbd package has been rebased to upstream version 1.3.1. This version brings the following changes:
  • Adds commands to test and query watchdog devices
  • Overhauls the command-line options and configuration file
  • Properly handles off actions instead of reboot (BZ#1499864)

Cluster status now shows by default when a resource action is pending

Pacemaker supports a record-pending option that previously defaulted to false, meaning that cluster status would only show the current status of a resource (started or stopped). Now, record-pending defaults to true, meaning that cluster status may also show when a resource is in the process of starting or stopping. (BZ#1461976)

clufter rebased to version 0.77.0

The clufter packages have been upgraded to upstream version 0.77.0, which provides a number of bug fixes, new features, and user experience enhancements over the previous version. Among the notable updates are the following:
  • When using clufter to translate an existing configuration with the pcs2pcscmd-needle command in the case where the corosync.conf equivalent omits the cluster_name option (which is not the case with standard `pcs`-initiated configurations), the contained pcs cluster setup invocation no longer causes cluster misconfiguration with the name of the first given node interpreted as the required cluster name specification. The same invocation will now include the --encryption 0|1 switch when available, in order to reflect the original configuration accurately.
  • In any script-like output sequence such as that produced with the ccs2pcscmd and pcs2pcscmd families of clufter commands, the intended shell interpreter is now emitted in a valid form, so that the respective commented line can be honored by the operating system. (BZ#1381531)
  • The clufter tool now also covers some additional recently added means of configuration as facilitated with pcs (heuristics for a quorum device, meta attributes for top-level bundle resource units) when producing the sequence of configuring pcs commands to reflect existing configurations when applicable.
For information on the capabilities of clufter, see the clufter(1) man page or the output of the clufter -h command. For examples of clufter usage, see the following Red Hat Knowledgebase article: https://access.redhat.com/articles/2810031. (BZ#1509381)

Support for Sybase ASE failover

The Red Hat High Availability Add-On now provides support for Sybase ASE failover through the ocf:heartbeat:sybaseASE resource. To display the parameters you can configure for this resource, run the pcs resource describe ocf:heartbeat:sybaseASE command. For more information on this agent, see the ocf_heartbeat_sybaseASE(7) man page. (BZ#1436189)