Upgrading DataStax Enterprise 6.7 to 6.8

Upgrade restrictions and limitations

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.

Preparing to upgrade

Follow these steps to prepare each node for the upgrade:

1. Upgrade to the latest patch release on your current version. Fixes included in the latest patch release can simplify the upgrade process.
   Get the current DSE version:

   bin/dse -v
   current_dse_version

2. Familiarize yourself with the changes and features in the new release:
   • DataStax Enterprise 6.8 release notes.
   • General upgrading advice for any version. Be sure to read 6.8 NEWS.txt all the way back to your current version.
   • DataStax Enterprise changes in 6.8 CHANGES.txt.
   • DataStax driver changes.
3. Before upgrading, be sure that each node has adequate free disk space.
   Determine current DSE data disk space usage:

   sudo du -sh /var/lib/cassandra/data/
   3.9G	/var/lib/cassandra/data/

   Determine available disk space:

   sudo df -hT /
   Filesystem     Type  Size  Used Avail Use% Mounted on
   /dev/sda1      ext4   59G   16G   41G  28% /

   Important: The required space depends on the compaction strategy. See Disk space
4. Upgrade the SSTables on each node to ensure that all SSTables are on the current version:

   nodetool upgradesstables

   Warning: Failure to upgrade SSTables when required results in a significant performance impact and increased disk usage.

   Tip: 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. DataStax recommends running the upgradesstables command on one node at a time or when using racks, one rack at a time.

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

5. Ensure that keyspace replication factors are correct for your environment:

   cqlsh --execute "DESCRIBE KEYSPACE keyspace-name;" | grep "replication"
   CREATE KEYSPACE keyspace-name WITH replication = {'class': 'NetworkTopologyStrategy, 'replication_factor': '3'}  AND durable_writes = true;

   • Check the keyspace replication factor for analytics keyspaces.
   • Check the keyspace replication factor for system_auth and dse_security keyspaces.
6. Verify the Java runtime version and upgrade to the recommended version.

   java -version
   openjdk version "1.8.0_222"
   OpenJDK Runtime Environment (build 1.8.0_222-8u222-b10-1ubuntu1~18.04.1-b10)
   OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)

   • Recommended: OpenJDK 8 (1.8.0_151 minimum)
     Note: Recommendation changed due to the end of public updates for Oracle JRE/JDK 8. See Oracle Java SE Support Roadmap.
   • Supported: Oracle Java SE 8 (JRE or JDK) (1.8.0_151 minimum)
   Important: Although Oracle JRE/JDK 8 is supported, DataStax does more extensive testing on OpenJDK 8.
7. Run nodetool repair to ensure that data on each replica is consistent with data on other nodes:

   nodetool repair -pr

8. Back up any customized configuration files since they may be overwritten with default values during installation of the new version.
   Tip: If you backed up your installation using instructions in Backing up and restoring DSE, your original configuration files are included in the archive.

Upgrade steps

1. Flush the commit log of the current installation:

   nodetool drain

2. Stop the node:
   • Package installations:

     sudo service dse stop

   • Tarball installations:

     installation_dir/bin/dse cassandra-stop

3. Use the appropriate method to install the new product version on a supported platform:
   • Package installer using YUM
   • Package installer using APT
   • Binary tarball installer
4. To configure the new version:
   1. Compare changes in the new configuration files with the backup configuration files after the upgrade but before restarting, remove deprecated settings, and update any new settings if required.
      Warning: Do not simply replace new configuration files with old. Rather compare your old files to the new files and make any required changes.
      Tip: Use the DSE yaml_diff tool to compare backup YAML files with the upgraded YAML files:

      cd /usr/share/dse/tools/yamls

      ./yaml_diff path/to/yaml-file-old path/to/yaml-file-new
      ...
       CHANGES 
      =========
      authenticator:
      - AllowAllAuthenticator
      + com.datastax.bdp.cassandra.auth.DseAuthenticator
      
      authorizer:
      - AllowAllAuthorizer
      + com.datastax.bdp.cassandra.auth.DseAuthorizer
      
      roles_validity_in_ms:
      - 2000
      + 120000
      ...

      cassandra.yaml changes

      Internode encryption settings

      Important: For security reasons, DSE 6.8 only allows the TLS encryption option protocol:

      server_encryption_options:
          ...
          protocol: TLS

      See https://www.oracle.com/technetwork/java/javase/8u31-relnotes-2389094.html#newft for details.

      Client encryption settings

      Important: For security reasons, DSE 6.8 only allows the TLS encryption option protocol:

      client_encryption_options:
          ...
          protocol: TLS

      See https://www.oracle.com/technetwork/java/javase/8u31-relnotes-2389094.html#newft for details.

5. Start the node.
   • Package installations:

     sudo service dse start

   • Tarball installations:

     installation_dir/bin/dse cassandra

6. Verify that the upgraded datacenter names match the datacenter names in the keyspace schema definition:
   • Get the node's datacenter name:

     nodetool status | grep "Datacenter"
     Datacenter: datacenter-name

   • Verify that the node's datacenter name matches the datacenter name for a keyspace:

     cqlsh --execute "DESCRIBE KEYSPACE keyspace-name;" | grep "replication"
     CREATE KEYSPACE keyspace-name WITH replication = {'class': 'NetworkTopologyStrategy, 'datacenter-name': '3'};

7. Review the logs for warnings, errors, and exceptions:

   grep -w 'WARNING\|ERROR\|exception' /var/log/cassandra/*.log

   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.

   Tip: Non standard log locations are configured in dse-env.sh.
8. Repeat the upgrade process on each node in the cluster following the recommended order.
9. After the entire cluster upgrade is complete: upgrade the SSTables on one node at a time or, when using racks, one rack at a time.
   Warning: Failure to upgrade SSTables when required results in a significant performance impact and increased disk usage and possible data loss. Upgrading is not complete until the SSTables are upgraded.

   nodetool upgradesstables

   Tip: 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. DataStax recommends running the upgradesstables command on one node at a time or when using racks, one rack at a time.
   Important: You can run the upgradesstables command before all the nodes are upgraded as long as you run the command on only one node at a time or when using racks, one rack at a time. Running upgradesstables on too many nodes at once will degrade performance.

General post upgrade steps

After all nodes are upgraded:

1. If you use the OpsCenter Repair Service, turn on the Repair Service.
2. DSE 6.7 introduces, and enables by default, the DSE Metrics Collector, a diagnostics information aggregator used to help facilitate DSE problem resolution. For more information on the DSE Metrics Collector, or to disable metrics collection, see DataStax Enterprise Metrics Collector.
3. Spark Jobserver uses DSE custom version 8.0.4.45. Ensure that applications use the compatible Spark Jobserver API from the DataStax repository.

Locking DSE package versions

If you have upgraded a DSE package installation, you can prevent future unintended upgrades.

RHEL yum installations

sudo yum versionlock clear

For details on the versionlock command, see http://man7.org/linux/man-pages/man1/yum-versionlock.1.html.

Debian apt-get installations

sudo apt-mark hold dse-*

sudo apt-mark unhold dse-*

For details on the apt-mark command, see http://manpages.ubuntu.com/manpages/bionic/man8/apt-mark.8.html.