rs.addArb()
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Description
rs.addArb(host)Adds a new arbiter to an existing replica set.
rs.add(<host>, true)is functionally the same asrs.addArb(<host>). You can use these commands interchangeably.Warning
Avoid deploying more than one arbiter in a replica set. See Concerns with Multiple Arbiters.
To add an arbiter to an existing replica set:
Typically, if there are two or fewer data-bearing members in the replica set, you might need to first set the cluster wide write concern for the replica set.
See cluster wide write concern for more information on why you might need to set the cluster wide write concern.
You do not need to change the cluster wide write concern before starting a new replica set with an arbiter.
The
rs.addArb()method takes the following parameter:ParameterTypeDescriptionhoststringSpecifies the hostname and optionally the port number of the arbiter member to add to replica set.
IP Binding
Warning
Before you bind your instance to a publicly-accessible IP address, you must secure your cluster from unauthorized access. For a complete list of security recommendations, see Security Checklist for Self-Managed Deployments. At minimum, consider enabling authentication and hardening network infrastructure.
MongoDB binaries, mongod and mongos, bind
to localhost by default. If the net.ipv6 configuration file
setting or the --ipv6 command line option is set for the binary,
the binary additionally binds to the localhost IPv6 address.
By default mongod and mongos that are
bound to localhost only accept connections from clients that are
running on the same computer. This binding behavior includes
mongosh and other members of your replica set or sharded
cluster. Remote clients cannot connect to binaries that are bound only
to localhost.
To override the default binding and bind to other IP addresses, use the
net.bindIp configuration file setting or the --bind_ip
command-line option to specify a list of hostnames or IP addresses.
Warning
Starting in MongDB 5.0, split horizon DNS nodes that are
only configured with an IP address fail startup validation and
report an error. See disableSplitHorizonIPCheck.
For example, the following mongod instance binds to both
the localhost and the hostname My-Example-Associated-Hostname, which is
associated with the IP address 198.51.100.1:
mongod --bind_ip localhost,My-Example-Associated-Hostname
In order to connect to this instance, remote clients must specify
the hostname or its associated IP address 198.51.100.1:
mongosh --host My-Example-Associated-Hostname mongosh --host 198.51.100.1
Important
To avoid configuration updates due to IP address changes, use DNS hostnames instead of IP addresses. It is particularly important to use a DNS hostname instead of an IP address when configuring replica set members or sharded cluster members.
Use hostnames instead of IP addresses to configure clusters across a split network horizon. Starting in MongoDB 5.0, nodes that are only configured with an IP address fail startup validation and do not start.