Upgrades for DataStax Enterprise 5.0.x patch releases

General recommendations

Be sure to read the DataStax Enterprise 5.0 release notes.

General restrictions and limitations during the upgrade process

Restrictions and limitations apply while a cluster is in a partially upgraded state. The cluster continues to work as though it were on the earlier version of DataStax Enterprise until all of the nodes in the cluster are upgraded.

Restrictions for all nodes during an upgrade

• Do not enable new features.
• Do not run nodetool repair.
• Do not bootstrap or decommission nodes.
• Failure to upgrade SSTables when required results in a significant performance impact and increased disk usage. Upgrading is not complete until the SSTables are upgraded.

Note: Nodes on different versions might show a schema disagreement during an upgrade.

DSE Analytics (Hadoop and Spark) upgrade restrictions

• Do not run analytics jobs until all nodes are upgraded.
• Kill all Spark worker processes before you stop the node and install the new version.

DSE Search (Solr) upgrade restrictions and limitations

• Do not update schemas.
• Do not reindex DSE Search nodes during upgrade.
• Do not issue these types of queries during a rolling restart: DDL or TRUNCATE.

Security upgrade restrictions

• Do not change security credentials or permissions until after the upgrade is complete.
• If you are not already using Kerberos, do not set up Kerberos authentication before upgrading. First upgrade the cluster, then set up Kerberos.

DSE Graph

• Because DSE Graph is generally run with other workloads, follow the same upgrade limitations for those workloads.
• Do not create or update any graph or other schemas during the upgrade.
• You can safely ignore gremlin and graph related errors during the upgrade.

Advanced preparation for upgrading DSE 5.0.0-5.0.8 to 5.0.9 and later 5.0.x releases

This section applies only when upgrading from DSE 5.0.0-5.0.8 to 5.0.9 and later 5.0.x releases.

The messaging protocol version in DSE 5.0.9 and DSE 5.1.2 has been changed to VERSION_3014. Schema migrations rely on exact messaging protocol versions. To accommodate schema changes that might occur during the upgrade, force a backward compatible messaging protocol.

1. Before you upgrade, restart the node with this start-up parameter:

   -Dcassandra.force_3_0_protocol_version=true

   For example:

   installation_location/bin/dse cassandra "-Dcassandra.force_3_0_protocol_version=true"

   Note: While mixed versions exist during the upgrade, do not add or remove columns from existing tables.
2. After the upgrade is complete on all nodes, follow the upgrade steps to restart nodes without this start-up parameter.

Preparing to upgrade

1. Back up your data.

   OpsCenter provides a Backup Service that manages enterprise-wide backup and restore operations for DataStax Enterprise clusters. OpsCenter 6.5 and later is recommended.

2. Verify your current product version:

   dse -v

3. Upgrade to the latest patch release on your current version.

   The latest version of DSE 5.0 is 5.0.15.

   You can use OpsCenter 6.5 Lifecycle Manager (LCM) to clone a configuration profile and run an upgrade job on a datacenter or node. Upgrade jobs are supported for upgrades within a DSE release series for DSE 5.0.x and later.

4. Before upgrading, be sure that each node has ample free disk space.

   The required space depends on the compaction strategy. See Disk space.

5. Familiarize yourself with the changes and features in DataStax Enterprise and Apache Cassandra™:
   • DataStax Enterprise release notes for the upgrade version and complete all required actions.

     DSE release notes include required planning, components, changes and enhancements, known issues, and resolved issues. See 5.1, 5.0, and 4.8.

   • General upgrading advice for any version and New features for Apache Cassandra in NEWS.txt. Be sure to read the NEWS.txt all the way back to your current version.
   • Apache Cassandra™ changes in CHANGES.txt.
   • DataStax Enterprise production-certified changes to Apache Cassandra in the DSE release notes.
   • DataStax driver changes.
6. DSE Search nodes:
   • Tune the schema before you upgrade. For DSE 5.0.10 and later, all field definitions in the schema are validated and must be DSE Search compatible, even if the fields are not indexed, have docValues applied, or used for copy-field source.
   • The default behavior of automatic resource generation includes all columns. To improve performance, take action to prevent the fields from being loaded from the database to the indexing path. In the schema, remove or comment out unused fields.

   • All unique key elements must be indexed in the Solr schema. To verify unique key elements, review schema.xml to ensure that all unique key fields must have indexed=true.

   • If you changed the schema, do a full reindex.
7. Back up the configuration files you use to a folder that is not in the directory where you normally run commands.

   The configuration files are overwritten with default values during installation of the new version.

Upgrade steps

1. Run nodetool repair to ensure that data on each replica is consistent with data on other nodes.
2. Upgrade order matters. Upgrade nodes in this order:
   • In multiple datacenter clusters, upgrade every node in one datacenter before upgrading another datacenter.
   • Upgrade the seed nodes within a datacenter first.

     For DSE Analytics nodes using DSE Hadoop, upgrade the Job Tracker node first. Then upgrade Hadoop nodes, followed by Spark nodes.

   • Upgrade nodes in this order:
     1. DSE Analytics datacenters
     2. Transactional/DSE Graph datacenters
     3. DSE Search datacenters
   With a few exceptions, the cluster continues to work as though it were on the earlier version of DataStax Enterprise until all of the nodes in the cluster are upgraded. Upgrade and restart the nodes one at a time. Other nodes in the cluster continue to operate at the earlier version until all nodes are upgraded.
3. Run nodetool drain to flush the commit log of the old installation:

   nodetool drain -h hostname

   This step saves time when nodes start up after the upgrade, and prevents DSE Search nodes from having to reindex data.

4. Stop the node.
5. Use the appropriate method to install the new product version.
6. To configure the new product version:
   1. Compare your backup configuration files to the new configuration files:
      • Look for any deprecated, removed, or changed settings.
      • Be sure you are familiar with the Apache Cassandra and DataStax Enterprise changes and features in the new release.
      • Check for any other configuration files that you might have changed. See Default file locations for Installer-Services and package installations or Installer-No Services and tarball installations.
   2. Merge the applicable modifications into the new version.
7. Start the node.
8. Verify that the upgraded datacenter names match the datacenter names in the keyspace schema definition:

   nodetool status

9. Review the logs for warnings, errors, and exceptions.

   Warnings, errors, and exceptions are frequently found in the logs when starting an upgraded node. Some of these log entries are informational to help you execute specific upgrade-related steps. If you find unexpected warnings, errors, or exceptions, contact DataStax Support.

10. Repeat the upgrade and restart on each node in the cluster following the recommended upgrade order.

    Upgrading and restarting each node is called a rolling restart.

11. After the new version is installed on each node, DataStax recommends upgrading the SSTables on each node.

    Upgrading SSTables is recommended for optimal performance, but is not required for patch releases.

    nodetool upgradesstables

    If the SSTables are already on the current version, the command returns immediately and no action is taken.

    Use the --jobs option to set the number of SSTables that upgrade simultaneously. The default setting is 2, which minimizes impact on the cluster. Set to 0 to use all available compaction threads. For information about nodetool upgradesstables, including how to speed it up, see the DataStax Support KB article Nodetool upgradesstables FAQ.

12. This step applies only from DSE 5.0.0-5.0.9 to 5.0.10 and later 5.0.x patch releases:
    To continue running incremental repairs, use nodetool repair -inc.

    Important: To migrate away from incremental repairs to enable non-incremental full (-full) or partition (-pr) repair, you must set all SSTables on all nodes as unrepaired using nodetool mark_unrepaired before running your first repair after upgrading.
13. If you use the OpsCenter Repair Service, turn on the Repair Service.