+ :ref:`Primary Affinity <rados_ops_primary_affinity>`
+ The characteristic of an OSD that governs the likelihood that
+ a given OSD will be selected as the primary OSD (or "lead
+ OSD") in an acting set. Primary affinity was introduced in
+ Firefly (v. 0.80). See :ref:`Primary Affinity
+ <rados_ops_primary_affinity>`.
+
+ Quorum
+ Quorum is the state that exists when a majority of the
+ :ref:`Monitors<arch_monitor>` in the cluster are ``up``. A
+ minimum of three :ref:`Monitors<arch_monitor>` must exist in
+ the cluster in order for Quorum to be possible.
+