Node types and capabilities
===========================

A PGD cluster can contain several different types of node, each with its
own role. This section describes the different types of node that can be
configured in a PGD cluster.

-  :ref:`Overview of durability options <Overview of durability options>`  is an overview the kinds of node that can exist in PGD
   clusters and their associated roles.

-  :ref:`Witness nodes <Witness nodes>`  looks at the witness node, a special class of PGD node,
   dedicated to establishing consensus in a group.

-  :ref:`Logical standby nodes <Logical standby nodes>`  shows how to efficiently keep a node on standby
   synchronized and ready to step in as a primary in the case of
   failure.

-  :ref:`Subscriber-only nodes and groups <Subscriber-only nodes and groups>`  looks at how subscriber-only nodes work with
   subscriber-only groups, how they boost read scalability and the
   different options for configuring them.

.. toctree::
  :maxdepth: 3

  PGD_Features--nodes--overview
  PGD_Features--nodes--witness_nodes
  PGD_Features--nodes--logical_standby_nodes
  PGD_Features--nodes--subscriber_only--index