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- Migrate Config Servers with the Same Hostname
Migrate Config Servers with the Same Hostname¶
This procedure migrates a config server in a sharded cluster to a new system that uses the same hostname.
To migrate all the config servers in a cluster, perform this procedure
for each config server separately and migrate the config servers in
reverse order from how they are listed in the mongos
instances’ configdb
string. Start with the last config server
listed in the configdb
string.
Shut down the config server.
This renders all config data for the sharded cluster “read only.”
Change the DNS entry that points to the system that provided the old config server, so that the same hostname points to the new system. How you do this depends on how you organize your DNS and hostname resolution services.
Copy the contents of
dbpath
from the old config server to the new config server.For example, to copy the contents of
dbpath
to a machine namedmongodb.config2.example.net
, you might issue a command similar to the following:Start the config server instance on the new system. The default invocation is:
When you start the third config server, your cluster will become writable and it will be able to create new splits and migrate chunks as needed.