Performing a rolling upgrade

You can upgrade Pega Platform by performing a rolling upgrade (rolling restart) that keeps your system available during the upgrade process. You remove nodes from the load balancer, shut them down, upgrade, and restart each node one by one. When you have upgraded half of the nodes, you add them back to the load balancer.

1. Follow these general steps to upgrade your database. For detailed information about each step, see your Upgrade Guide for performing an out-of-place upgrade.
   1. Disable rule saving.
   2. Migrate the PegaRULES schema to a temporary schema.
   3. Update the new rules schema, for example, a framework or application update.
   4. Copy the new rule schema to the production database.
2. Upgrade half of the nodes one by one. For each node, do the following steps:
   1. Quiesce the node and remove it from the load balancer, following the instructions in Quiescing a node with immediate drain or Quiescing a node with slow drain, depending on your cluster configuration.
   2. Shut down the node.
   3. Configure the node to connect to the updated rules schema. For more information, see your Upgrade Guide for migrating the rules schema.
   4. Restart the node.
   5. Perform any needed post-upgrade activities and tests.
3. Change the load balanced configuration to point to the upgraded nodes.
4. Do step 2 for the remaining nodes, and then reactivate them in the load balancer.