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- Adjust Priority for Replica Set Member
Adjust Priority for Replica Set Member¶
To change the value of the
priority
in the replica set
configuration, use the following sequence of commands in the
mongo
shell:
The first operation uses rs.conf()
to set the local variable
cfg
to the contents of the current replica set configuration, which
is a document. The next three operations change the
priority
value in the cfg
document for the first three members configured in the members
array. The final operation calls
rs.reconfig()
with the argument of cfg
to initialize the
new configuration.
When updating the replica configuration object, access the replica set
members in the members
array with the
array index. The array index begins with 0
. Do not confuse
this index value with the value of the
_id
field in each document in
the members
array.
If a member has priority
set
to 0
, it is ineligible to become primary and will not seek
election. Hidden members,
delayed members, and
arbiters all have
priority
set to 0
.
All members have a priority
equal to 1
by default.
The value of priority
can be
any floating point (i.e. decimal) number between 0
and 1000
.
Priorities are only used to determine the preference in election. The
priority value is used only in relation to other members. With the
exception of members with a priority of 0
, the absolute value of
the priority
value is
irrelevant.
Replica sets will preferentially elect and maintain the primary status
of the member with the highest
priority
setting.
Warning
Replica set reconfiguration can force the current primary to step down, leading to an election for primary in the replica set. Elections cause the current primary to close all open client connections.
Perform routine replica set reconfiguration during scheduled maintenance windows.
See also
The Replica Reconfiguration Usage example revolves around
changing the priorities of the members
of a replica set.