Within an online upgrade, the upgrade process can take place without taking down the cluster or the associated application. This means that the cluster and applications can continue to function while you upgrade the individual nodes within the cluster.
For information on upgrading from Couchbase Server 1.8 to Couchbase Server 2.0, see Section 2.7, “Upgrades Notes 1.8.1 to 2.0”. Upgrades from Couchbase Server 1.8 to 2.0 Beta or earlier releases are not supported.
To perform an online upgrade of your cluster:
Choose a node to remove from the cluster and upgrade. You can upgrade one node at a time, or if you have enough cluster capacity, two nodes at a time.
On the Manage->Server Nodes screen, click the . This marks the server for removal from the cluster, but does not actually remove it.
The Pending Rebalance will show the number of servers that require a rebalance to remove them from the cluster. Click the button.
This will start the rebalance process. Once rebalancing has been completed, the Server Nodes display should display only the remaining (active) nodes in your cluster.
Perform a standard node upgrade to the new version of Couchbase Server. See Section 2.7.3, “Node Upgrade Process” for details.
Couchbase Server should be started automatically after the upgrade. If not, restart the Couchbase Server process, using the methods described in Section 3.2, “Startup and Shutdown of Couchbase Server” .
With the node upgraded, you need to add the node back to the cluster.
On an existing node within the running cluster, navigate to the Manage->Server Nodes page. Click the button. You will be prompted to enter the IP address and username/password of the server to add back to the cluster.
For Couchbase 2.0.2 you can provide either a hostname or IP Address for the node you want to add. For more information, see Section 2.4, “Using Hostnames with Couchbase Server”.
The Pending Rebalance count will indicate that servers need to be rebalanced into the cluster. Click to rebalance the cluster, and bring the node back into production.
You will need to repeat the above sequence for each node within the cluster in order to upgrade the entire cluster to the new version.