Important Points to Note before Performing Rolling Upgrades

You may have to change your applications before starting the rolling upgrade so that the code will work in a mixed-version cluster. See Known Incompatibilities with Previous Releases.

Do not change your applications to take advantage of features in the new version until the rolling upgrade is committed because new features are not available until then.

Do not perform any manual merges in a mixed-version cluster.

Do not configure a merge blackout before performing a rolling upgrade, because automatic merges need to occur during the upgrade process.

Disable reindexing before performing a rolling upgrade.

Upgrade the disaster recovery cluster first so that the newer version of the software can receive fragments and journal frames encoded on the master cluster.

The cluster needs High Availability (HA) configured for Security, Schema, and other auxiliary databases.

The primary security, schema, and auxiliary forests must be on the same host, and that host must be the first host that you upgrade when upgrading a cluster.

Before stopping the MarkLogic Server process on a node, configure your load balancer to divert transactions away from the node being upgraded, and allow all existing and queued transactions to complete.

Before stopping the MarkLogic Server process on a node, make sure that all acting replica forests on the other nodes have caught up in replicating content.

Mounting a forest takes time. Prioritize the failover of forests for your security, schema, and other auxiliary databases.

In a mixed-version cluster, before the upgrade has been committed, upgraded nodes are read-only. This status prevents configuration changes from being made from that node.

Running your cluster in an uncommitted state is equivalent to running it in the previous (earlier) version of MarkLogic Server.

A cluster will be a mixed-version cluster for only a short time. During this time, do not make application code changes or configuration changes like these:

• Changes to index, forest, database, application server, host, group, and cluster settings.

• Changes to security settings such adding, changing, or deleting roles, users, privileges, credentials, certificates, and so on.

• Adding, removing, or updating TDE templates.

• Adding, removing, or updating redaction rules.

You can change error log settings and add trace events to debug issues during rolling upgrades.

After committing a rolling upgrade, you cannot roll back to the earlier version of MarkLogic Server.

You must upgrade the security database after you have committed the new version of MarkLogic Server.