readability: rs-priority-0

source/core/replica-set-priority-0-member.txt

@@ -6,69 +6,53 @@ Priority 0 Replica Set Members
 
 .. default-domain:: mongodb
 
-*Priority 0* members contain copies of the :term:`primary's <primary>`
-data set, can accept read operations from client applications, and vote
-in :ref:`elections <replica-set-elections>` for primary. However,
-*priority 0* members **cannot** become primary in an election, and
-*priority 0* members **do not** trigger elections.
-
-For example, you may consider setting the priority of a member to 0
-when you wish to to prevent :term:`secondaries <secondary>` located
-outside of the main data centers from ever becoming primary.
-
-.. example::
-
-   In the following three member replica set, the first data center
-   contains the primary and a secondary whereas the second data center
-   contains a *priority 0* member that cannot become a primary.
-
-   .. include:: /images/replica-set-three-members-geographically-distributed.rst
+A *priority 0* member is similar to a secondary except that it cannot
+become a :term:`primary` and it cannot *trigger* an :term:`election`.
+The member otherwise functions as a secondary. It maintains a copy of
+the data set, accepts read operations, and votes in elections. You can
+use the *priority 0* setting to prevent :term:`secondaries <secondary>`
+located outside the main data center from becoming primary.
+
+In the following three-member replica set, the first data center
+contains the primary and a secondary. The second data center contains a
+*priority 0* member that cannot become primary.
+
+.. include:: /images/replica-set-three-members-geographically-distributed.rst
+
+Priority 0 Members as Standbys
+------------------------------
+
+A *priority 0* member can function as a standby. In some replica sets,
+it might not be possible to add a new member in a reasonable amount of
+time. A standby holds an up-to-date copy of the data for the purpose of
+replacing a secondary that fails or goes offline.
+
+In many cases, you need not configure a standby as *priority 0*. But in
+sets with varied hardware availability or :ref:`geographic distribution
+<replica-set-geographical-distribution>`, a *priority 0* standby ensures
+that only qualified members become primary.
+
+A priority 0* standby may also be valuable when your primary and any hot
+standbys have different hardware specifications than the other members
+of the set. In these cases, deploy a member as a *priority 0* member to
+ensure it can vote in elections but not become primary. (You also can
+use a :ref:`hidden <replica-set-hidden-members>` member for this
+purpose.)
+
+If your set already has seven voting members, set the standby's
+:data:`~local.system.replset.members[n].votes` value to ``0``. This
+ensures it does not vote in elections.
+
+Priority 0 Members and Failover
+-------------------------------
+
+When configuring a *priority 0* member, consider the likely failover
+scenarios, such as inter-site network partitions. Always ensure that
+your main data center contains both a quorum of voting members and
+contains members that are eligible to be primary.
 
 Configuration
 -------------
 
-A *priority 0* member has its
-:data:`~local.system.replset.members[n].priority` equal to ``0`` in its
-member configuration:
-
-.. code-block:: javascript
-   :emphasize-lines: 4
-
-   {
-      "_id" : <num>,
-      "host" : <hostname:port>,
-      "priority" : 0
-   }
-
-Applications
-------------
-
-*Priority 0* members can function as cold standbys in a replica
-set. In this role, a member of a replica set holds a copy of the data
-but cannot become primary without manual intervention. For some sets,
-it may not be possible to initialize a new member in a reasonable
-amount of time. In these situations, it may be useful to maintain a
-cold standby with an up-to-date copy for the purpose of replacing
-another member in the replica set. In most cases, these members can be
-ordinary members of the replica set, but in larger sets, with varied
-hardware availability, or given some patterns of :ref:`geographical
-distribution <replica-set-geographical-distribution>`, you may want to
-use a *priority 0* or a :doc:`hidden member
-</core/replica-set-hidden-member>` to maintain an extra copy of the data.
-
-*Priority 0* members may be valuable when your primary and any hot
-standbys have different hardware specification than the other members
-of the set. In these cases, deploy members as a *priority 0* member
-or a :ref:`hidden <replica-set-hidden-members>` member to ensure that
-they will vote in elections but will never be eligible to become
-primary. If your set already has ``7`` voting members, set the
-:data:`~local.system.replset.members[n].votes` value to ``0`` for the
-cold standby members, so that they won't vote in elections.
-
-When configuring *priority 0* members, consider the likely failover
-scenarios, such as inter-site network partitions. Always ensure that
-there will be members eligible for election as primary *and* a quorum
-of voting members in the main facility.
-
 To configure a *priority 0* member, see
 :doc:`/tutorial/configure-secondary-only-replica-set-member`.

source/tutorial/configure-secondary-only-replica-set-member.txt

@@ -12,11 +12,20 @@ detailed description of secondary-only members and their purposes, see
 :doc:`/core/replica-set-priority-0-member`.
 
 To configure a member as secondary-only, set its
-:data:`~local.system.replset.members[n].priority` value to ``0``. Any
+:data:`~local.system.replset.members[n].priority` value to ``0`` in its member configuration. Any
 member with a :data:`~local.system.replset.members[n].priority` equal to
 ``0`` will never seek :ref:`election <replica-set-elections>` and cannot
 become primary in any situation.
 
+.. code-block:: javascript
+   :emphasize-lines: 4
+
+   {
+      "_id" : <num>,
+      "host" : <hostname:port>,
+      "priority" : 0
+   }
+
 MongoDB does not permit the current :term:`primary` to have a priority
 of ``0``. To prevent the current primary from again becoming a primary,
 you must first step down the current primary using