Replacing a Node

At some point, for various reasons, you might need to replace a node in your Riak cluster (which is different from recovering a failed node). Here is the recommended way to go about replacing a node.

Back up your data directory on the node in question. In this example scenario, we'll call the node riak4:
```
sudo tar -czf riak_backup.tar.gz /var/lib/riak /etc/riak
```
Download and install Riak on the new node you wish to bring into the cluster and have replace the riak4 node. We'll call this node riak7 for the purpose of this example.
Start the new riak7 node with riak start:
```
riak start
```
Plan the join of the new riak7 node to an existing node already participating in he cluster; for example riak0 with the riak-admin cluster join command executed on the the new riak7 node:
```
riak-admin cluster join riak0
```
Plan the replacement of the existing riak4 node with the new riak7 node using the riak-admin cluster replace command:
```
riak-admin cluster replace riak4 riak7
```
Examine the proposed cluster changes with the riak-admin cluster plan command executed on the the new riak7 node:
```
riak-admin cluster plan
```
If the changes are correct, you can commit them with the riak-admin cluster commit command:
```
riak-admin cluster commit
```

If you need to clear the proposed plan and start over, use riak-admin cluster clear:

riak-admin cluster clear

Once you have successfully replaced the node, it should begin leaving the cluster. You can check on ring readiness after replacing the node with the riak-admin ringready and riak-admin member-status commands.

Ring Settling

You'll need to make sure that no other ring changes occur between the time when you start the new node and the ring settles with the new IP info.

The ring is considered settled when the new node reports true using the riak-admin ringready command.