OPTIONS

Replace Disabled Config Server

Overview

Sharded clusters use a group of three config servers to store cluster meta data, and all three config servers must be available to support cluster metadata changes that include chunk splits and migrations. If one of the config servers is unavailable or inoperable you must replace it as soon as possible.

This procedure replaces an inoperable config server in a sharded cluster. Use this procedure only to replace a config server that has become inoperable (e.g. hardware failure).

This process assumes that the hostname of the instance will not change. If you must change the hostname of the instance, use the procedure to migrate a config server and use a new hostname.

Considerations

In the course of this procedure never remove a config server from the configDB parameter on any of the mongos instances.

Procedure

1

Provision a new system, with the same IP address and hostname as the previous host.

You will have to ensure the new system has the same IP address and hostname as the system it’s replacing or you will need to modify the DNS records and wait for them to propagate.

2

Shut down one of the remaining config servers.

Copy all of this host’s dbPath path from the current system to the system that will provide the new config server. This command, issued on the system with the data files, may resemble the following:

rsync -az /data/configdb mongodb.config2.example.net:/data/configdb
3

If necessary, update DNS and/or networking.

Ensure the new config server is accessible by the same name as the previous config server.

4

Start the new config server.

mongod --configsvr