Upgrading Apache Cassandra to DDAC

Upgrade restrictions and limitations

Preparing to upgrade

Follow these steps to prepare each node for the upgrade:

1. Familiarize yourself with the changes and features in the new release:
   • DDAC release notes for 5.1 (equivalent to Cassandra 3.11).
   • General upgrade advice and Cassandra features in NEWS.txt.
   • Cassandra changes in CHANGES.txt.
2. 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
3. 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.

4. 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.
5. Run nodetool repair to ensure that data on each replica is consistent with data on other nodes:

   nodetool repair -pr

6. Install the libaio package for optimal performance.
   RHEL platforms:

   sudo yum install libaio

   Debian:

   sudo apt-get install libaio1

7. 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. (2.1, 2.2, 3.0)
3. Uninstall Cassandra.
   Note: If you installed Cassandra from packages in APT or RPM repositories, you must remove the packages before setting up and installing DDAC.
   • For packages installed from APT repositories:

     sudo apt-get autoremove "dsc*" "cassandra*" "apache-cassandra*"

     This action shuts down Cassandra if it is still running.

   • For packages installed from Yum repositories:

     sudo yum remove "dsc*" "cassandra*" "apache-cassandra*"

     The old Cassandra configuration file might be renamed to cassandra.yaml.rpmsave, for example:

     warning: /etc/cassandra/default.conf/cassandra.yaml
     saved as /etc/cassandra/default.conf/cassandra.yaml.rpmsave

   • If Cassandra was installed with a binary tarball:

     ps auwx | grep cassandra

     sudo  kill cassandra_pid

     And then remove the Cassandra installation directory.

4. Install DDAC.
5. To configure the new product 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
      ...

6. If upgrading from Cassandra 3.11.2 or later, comment out the following parameters in cassandra.yaml if they exist:
   • enable_materialized_views
   • enable_sasi_indexes
   Tip: See configuration for the location of Cassandra configuration files.
7. Start the node:

   sudo bin/cassandra

   Tip: See DataStax Distribution of Apache Cassandra 3.11 start-up parameters for additional startup options.
8. 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'};

9. 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.
10. Run nodetool repair:

    bin/nodetool repair -pr

    Important: Be sure to run nodetool repair on each node in the datacenter.
11. Repeat the upgrade process on each node in the cluster following the recommended order.
12. 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.