- Red Hat Enterprise Linux (RHEL) 6 or 7 with the High Availability Add-On
Useful References and Guides
This guide lays out policies for the size and membership of RHEL High Availability clusters. Users of RHEL HA clusters should adhere to these policies in order to be eligible for support from Red Hat with the appropriate product support subscriptions.
Maximum cluster size: Red Hat provides support for up to 16 members in a single membership.
Maximum cluster size: Red Hat provides support for up to 32 members in a single membership with RHEL 7.7+ (see release notes). This enhancement does not apply to Resilient Storage Clusters utilizing clvmd, gfs2, dlm, cmirror, etc. The supported limit for Resilient Storage clusters is still 16 nodes.
- Members running
pacemaker_remotedo not go towards this limit of 16 nodes. See the section below for more details on
- This limit does not extend across multiple distinct clusters interacting with each other. For example, clusters coordinating resource management via
boothdo not have a total size limit of 16 across all clusters combined, but rather a limit of 16 nodes per cluster.
Minimum cluster size: Red Hat requires at least two nodes be configured in the membership for support to be provided on a given cluster.
- Red Hat will provide assistance with clusters that are temporarily in a degraded membership of only a single node, as long as the cluster was not designed with the expectation it would operate with a single node for long periods of time, and efforts are underway to return the cluster to a full-membership of at least two nodes.
- With issues arising out of a cluster running in a degraded single-node membership over a long period of time, Red Hat's assistance may be primarily focused on returning the cluster to a full membership of two or more nodes. In environments operating long-term with a single node, Red Hat may require reintroduction of additional members in order to assist with concerns in that environment.
pacemaker_remote nodes: Red Hat does not place an upper limit on the number of "remote" nodes that can operate in a cluster. However, if scaling to large volumes of remote nodes (many hundreds, or thousands) Red Hat recommends contacting Red Hat Support for guidance, and thoroughly testing behaviors and failure scenarios at peak loads.