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Chapter 38. Clustering

pcs now supports managing multi-site clusters that use Booth and ticket constraints

As a Technology Preview starting with Red Hat Enterprise Linux 7.3, the pcs tool enables you to manage multi-site clusters that use the Booth cluster ticket manager by using the pcs booth command. You can also set ticket constraints by using the pcs constraint ticket command to manage resources in multi-site clusters. It is also possible to manage ticket constraints in the web UI. (BZ#1305049, BZ#1308514)

Support for quorum devices in a Pacemaker cluster

Starting with Red Hat Enterprise Linux 7.3, you can configure a separate quorum device (QDevice) which acts as a third-party arbitration device for the cluster. This functionality is provided as a Technology Preview, and its primary use is to allow a cluster to sustain more node failures than standard quorum rules allow. A quorum device is recommended for clusters with an even number of nodes and highly recommended for two-node clusters. For information on configuring a quorum device, see https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/High_Availability_Add-On_Reference/. (BZ#1158805)

Support for clufter, a tool for transforming and analyzing cluster configuration formats

The clufter package, available as a Technology Preview in Red Hat Enterprise Linux 7, provides a tool for transforming and analyzing cluster configuration formats. It can be used to assist with migration from an older stack configuration to a newer configuration that leverages Pacemaker. For information on the capabilities of clufter, see the clufter(1) man page or the output of the clufter -h command. (BZ#1212909)

clufter rebased to version 0.59.5

The clufter packages, available as a Technology Preview, have been upgraded to upstream version 0.59.5, 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 converting the old cluster stack configuration into files for a Pacemaker stack or into the respective sequence of pcs commands with the ccs2pcs and ccs2pcscmd families of clufter commands, monitor action is properly propagated or added.
  • When converting configuration files for the Pacemaker stack using the corosync.conf file, either as a byproduct of converting CMAN-based configuration or with first-class input such as the *2pcscmd{,-needle} families of commands, the cluster name is propagated correctly. Previously, the cluster name was mistakenly dropped, resulting in a command that confused the name of the first cluster node for the name of the cluster as in, for example, pcs cluster setup --start --name node1 node2 node3.
  • When converting CMAN-based configuration into the parallel configuration for a Pacemaker stack with the ccs2pcs family of commands, accidentally broken values of attributes marked as having an ID type in the schema no longer occur.
  • When converting either CMAN or Pacemaker stack specific configuration into the respective sequence of pcs commands with the *2pcscmd families of commands, the clufter tool no longer suggests pcs cluster cib file --config, which does not currently work for subsequent local-modification pcs commands. Instead it suggests pcs cluster cib file.
  • The clufter tool outputs now may vary significantly depending on the specified distribution target since the tool now aligns the output with what the respective environment, such as the pcs version, can support. Because of this, your distribution or setup may not be supported, and you should not expect that one sequence of pcs commands that the clufter tool produces is portable to a completely different environment.
  • The clufter tool now supports several new features of the pcs tool, including quorum devices. Additionally, the clufter tool supports older features recently added to the pcs tool, including ticket constraints, and resource sets for colocation and order constraints. (BZ#1343661, BZ#1270740, BZ#1272570, BZ#1272592, BZ#1300014, BZ#1300050, BZ#1328078)

Support for Booth cluster ticket manager

Red Hat Enterprise Linux 7.3 provides support for a Booth cluster ticket manager as a technology preview. This allows you to configure multiple high availability clusters in separate sites that communicate through a distributed service to coordinate management of resources. The Booth ticket manager facilitates a consensus-based decision process for individual tickets that ensure that specified resources are run at only one site at a time, for which a ticket has been granted. For information on configuring multi-site clusters with the Booth ticket manager, see the https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/High_Availability_Add-On_Reference/ (BZ#1302087)