Apply a DSE 6.8 patch release

Improper upgrades can result in downtime, data loss, and other errors.

To minimize risk for an upgrade, review the entire upgrade guide before you begin, including warnings, restrictions, release notes, and all pre-upgrade, upgrade, and post-upgrade steps.

You must prepare all nodes in the cluster before upgrading any nodes. Failure to prepare all nodes can result in mismatched configurations, repair states, and schemas that can disrupt the upgrade process.

Use these instructions to apply a patch release for DataStax Enterprise (DSE) 6.8.

Upgrade path to avoid data loss

Data loss is possible when upgrading to a DSE 6.8 patch release.

Tuple data will be lost if you bypass 6.8.35.

Check your current version with dse -v, and then find the recommended path in the following table:

Current version Issue Upgrade path

6.8.0 to 6.8.35

Tuple data loss

To avoid tuple data loss:

  1. Upgrade to DSE 6.8.35.

  2. Upgrade all SSTables with nodetool upgradesstables -a and run sstablescrub --fix.

  3. Upgrade to the latest 6.8 patch release.

If you don’t have tuple data, you don’t need to stop at 6.8.35; you can upgrade directly to the latest 6.8 patch release.

6.8.36 or later

None

6.8.36 is beyond the tuple data loss boundary. You can proceed directly to the latest 6.8 patch release.

6.8.7 or 6.8.8

Retracted versions

DSE 6.8.7 and 6.8.8 were retracted due to a serious bug that is resolved in 6.8.9.

If you upgraded to 6.8.7 or 6.8.8 before they were retracted, you must do one or both of the following to stabilize your installation:

  • Set zerocopy_streaming_enabled=false in cassandra.yaml and perform a rolling restart.

  • Run nodetool upgradesstables -a on all nodes in your cluster before adding new nodes, running repair, or restoring from backups.

Then, upgrade to 6.8.9 or later as soon as possible. If you have tuple data, follow the upgrade path for versions 6.8.0 to 6.8.35 as described earlier in this table.

Avoid certain operations during the upgrade

The upgrade process for DSE can be completed with minimal downtime (ideally zero) by upgrading nodes in a rolling fashion: upgrade and restart one node at a time while the other nodes continue to operate.

The moment that you install the new version on one node in a cluster, the cluster enters a partially upgraded state. In this state, the cluster continues to operate as though all nodes are running the earlier, pre-upgraded version. The cluster remains in this state until you have upgraded all nodes in the cluster.

You must avoid or block the following operations during the upgrade to maintain cluster stability and prevent errors:

  • Don’t enable new features.

    This restriction includes net new features and existing features that you weren’t using previously. For example, don’t enable Change Data Capture (CDC) for the first time during an upgrade. Upgrade the entire cluster, and then enable the feature.

  • Don’t change credentials, permissions, or any other security settings unless explicitly instructed to do so.

    To preserve your existing configuration, you will transfer your existing security settings from your current configuration files to the new configuration files during the upgrade process. The new files might use different settings due to enhancements, deprecations, and removals between versions. This mapping is required for a successful upgrade, and it isn’t the same as an extraneous change to the security configuration.

    Examples of security changes to avoid include modifications to authenticators, authorizers, CQL roles, and CQL permissions. Postpone all such changes until after the upgrade.

    If you aren’t already using Kerberos, don’t set up Kerberos authentication immediately before upgrading. First upgrade the cluster, and then set up Kerberos. If you are already using Kerberos, you can continue to use it during the upgrade.

  • Don’t run repairs manually or automatically:

    • Disable all automated and scheduled repairs, including Reaper, crontab, and scripts that run nodetool repair.

    • Don’t manually run commands like nodetool repair.

    • Don’t repair SSTables while the cluster is in a partially upgraded state. Only repair SSTables before and after upgrading the entire cluster.

    You must complete the cluster-wide upgrade before the expiration of gc_grace_seconds (approximately 10 days by default) to ensure any post-upgrade repairs complete successfully.

    Attempting to run repairs on partially upgraded clusters can cause performance issues, data inconsistencies, and repair failures. If you absolutely must run repairs on a partially upgraded cluster, determine which SSTable formats and streaming protocols are supported on each node, and then thoroughly test your intended repair operation on an isolated non-production cluster. Small incremental repairs are less risky but they aren’t risk free.

  • Don’t add (bootstrap) new nodes or decommission existing nodes.

  • Don’t issue DDL-related queries like TRUNCATE.

    Depending on your infrastructure, workloads, and consistency levels, you might want to avoid other operations that could require excessive resources or coordination across mixed-version nodes. For example, BATCH operations can be resource intensive.

  • Don’t alter any schemas.

    Schema versions must be consistent across the cluster before starting the upgrade.

    Propagation of schema changes between mixed-version nodes can cause query failures, data consistency issues, and other errors. Take action to prevent schema changes from occurring during the upgrade process.

    During the upgrade, it is normal for nodes on different versions to show schema disagreements. These disagreements should resolve after the entire cluster is upgraded.

  • Don’t rebuild indexes during the upgrade.

  • Disable services that can cause data inconsistencies and interfere with the upgrade process:

    • Disable backup services, scheduled backups, and automated snapshots.

    • Disable the NodeSync Service for major and minor releases. For patch releases, disabling the NodeSync Service is optional.

  • If you disabled the Performance Service before the upgrade, don’t reenable it during the upgrade.

  • DSE Analytics nodes: Don’t run analytics jobs until all nodes are upgraded.

    When upgrading to a new major or minor version of DSE, all nodes in a DSE datacenter that run Spark must be on the same version of Spark, and the Spark jobs must be compiled for that version. To determine the Spark version, see the DSE release notes.

    Before reinitiating Spark jobs, all datacenters comprising a Spark cluster must be on the same upgraded DSE version. If any Spark jobs run against Graph keyspaces, don’t reinitiate Spark jobs until you have upgraded all Analytics and non-Analytics nodes in the entire cluster. When Graph keyspaces are involved, Spark jobs fail due to mixed Spark and DSE versions across all nodes.

Strict upgrade order for cluster stability

Don’t upgrade any nodes until you have completed the pre-upgrade steps on all nodes.

When upgrading nodes, always upgrade seed nodes before non-seed nodes.

To avoid cluster-wide downtime, you must upgrade and restart one node at a time in a specific order based on workload types and deployment architecture:

  1. For multi-cluster deployments, upgrade one cluster at a time.

  2. For multi-datacenter clusters, upgrade one datacenter at a time.

  3. If using racks, upgrade one rack at a time within a datacenter.

  4. Within a datacenter (or rack), upgrade one node at a time, starting with seed nodes.

  5. If using advanced workloads (Analytics, Graph, Search), upgrade datacenters or nodes according to the following workload type hierarchy:

    1. Upgrade DSE Analytics datacenters.

    2. Upgrade transactional (Cassandra) and DSE Graph datacenters.

    3. Upgrade DSE Search datacenters.

    If each datacenter has only one workload type, upgrade your datacenters in the given order. Within each datacenter, proceed rack-by-rack (if applicable) and node-by-node, starting with the seed nodes.

    If a datacenter has multiple workload types, upgrade nodes within that datacenter in the given order, starting with the seed nodes. If using racks, apply the hierarchy to each rack.

  6. Repeat until you have upgraded all nodes in all racks, datacenters, and clusters.

Use an isolated deployment to test the upgrade.

For example, in multi-datacenter clusters with an active-passive configuration, you can complete the entire upgrade process (pre-upgrade, upgrade, and post-upgrade) on the passive datacenter first, run performance tests on that datacenter, and then upgrade the active datacenter if the tests are successful. If the tests fail, you can destroy the passive datacenter and rebuild it without impacting the active datacenter.

Similarly, if you have a test deployment with no connectivity to your production nodes, datacenters, or clusters, then you can safely perform the entire upgrade process in that isolated deployment before rolling out the upgrade to your production deployment.

Prepare to upgrade

Before upgrading any node, you must prepare all nodes for the upgrade. Complete the pre-upgrade steps on every node in the recommended order. Following the recommended order ensures that you don’t miss any nodes, although some steps aren’t applicable to every node.

Some pre-upgrade steps provide information about actions that you must take later in the upgrade process. This information is given in advance because it might impact your upgrade plan. Be sure to revisit these steps at the appropriate time.

  1. Familiarize yourself with the changes and features in the new release, reviewing all releases between your current version and the latest 6.8 patch release as well as the latest Apache Cassandra® 3.11 patch releases:

  2. Make sure each node has adequate free disk space for the upgrade.

    The required overhead depends on the compaction strategy. For more information, see Disk space.

    1. Get the size of the DSE data directory:

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

    2. Check available space on disk:

      sudo df -hT /

      The following output includes one disk named /dev/sda1. Your output depends on your disk configuration.

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

    3. If necessary, make adjustments to your disks or data directory configuration to allow for more disk space.

  3. Upgrade all SSTables on all nodes.

    To avoid significant performance degradation and issues with incompatible SSTables formats, always upgrade SSTables before and after any database upgrade, including minor and patch releases.

    This process is recommended for all upgrades, and it is critical for upgrades that involve a major underlying Cassandra version change.

    On each node, run nodetool upgradesstables with the -a flag to ensure that all SSTables use the latest SSTable format and version for your current database version:

    nodetool upgradesstables -a

    DataStax recommends running the upgradesstables command on one node at a time or, when using racks, one rack at a time. Running the command on too many nodes at once can degrade performance.

    You can use the --jobs option to set the number of SSTables that upgrade simultaneously. The default setting is 2, which minimizes the impact on the cluster. Set to 0 to use all available compaction threads.

    If all SSTables are already on the latest version and format, the command returns immediately and takes no action.

    For more information about this command, see nodetool upgradesstables.

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

    nodetool repair -pr

    Repair nodes on a regular basis to minimize the overhead and time required for repair operations.

    If you use DSE OpsCenter, you can repair nodes with the Repair Service but you must disable the Repair Service before upgrading any nodes.

  5. Back up all DSE data and files, and then store the backups separately from your existing DSE installation.

    Backup your existing installation before every upgrade, regardless of the extent of the upgrade.

    To avoid data loss, you must store your backup configuration files in a separate directory from your DSE installation. The new version overwrites configuration files that are present in the installation directory, replacing all existing values with new default values.

    Examples of data and files to back up include:

    • SSTable snapshots

    • Commit logs

    • Logs

    • Configuration files

    • Encrypted table recovery data:

      • A snapshot of the entire dse_system keyspace with the encrypted_keys table

      • All system keys

    Some backup files are used during the upgrade process to align the new version with the previous version, and a complete backup is required if you need to rollback to the previous version or restore lost data.

    If your upgrade requires significant pre-upgrade changes, consider creating a backup before making those changes and again immediately before upgrading the first node. Create the final backup as close to the beginning of your upgrade as possible to ensure your backup contains the most recent configuration files and data.

    For instructions, see Back up and restore a DSE package installation or Back up and restore a DSE tarball installation.

Upgrade steps

Upgrade one node at a time in the recommended order. Following the recommended order minimizes downtime and ensures that you don’t miss any nodes.

  1. DSE Analytics nodes: Kill all Spark worker processes:

    for pid in $(jps | grep Worker | awk '{print $1}'); do kill -9 $pid; done

  2. Flush the commit log of the current installation:

    nodetool drain

  3. Stop the node.

  4. Install the new DSE 6.8 version, but don’t start DSE.

    Don’t start DSE yet. Before restarting the node, you must reconfigure DSE as explained in the next steps.

    If you use DSE OpsCenter, you can use Lifecycle Manager (LCM) to clone a configuration profile and run an upgrade job on a datacenter or node. This approach can help streamline the install and reconfiguration process.

    Use the same installation type as your current version. Mismatched installation types can cause problems with the upgrade.

  5. Configure the new DSE version by comparing the new configuration files to your backup configuration files.

    Patch releases are unlikely to introduce significant changes, but you must ensure that your existing settings are transferred to the new version. The extent of the changes depends on your workloads, previous configurations, and the number of patch releases between your current and new versions. For example:

    • Remove deprecated and removed settings.

    • Configure new settings.

    • Migrate previous custom configuration values to your new configuration files.

    • Modify previous configurations to account for changes described in the DSE release notes.

    You must use the new configuration files included with your new installation. Copy values from your old configuration files into the new files. Don’t overwrite entire files with the old files.

    For default configuration file locations in DSE 6.8, see Default file locations for package installations and Default file locations for tarball installations.

    You can use the yaml_diff tool to compare your backup YAML files with the new YAML files:

    cd /usr/share/dse/tools/yamls
    ./yaml_diff path/to/yaml-file-old path/to/yaml-file-new

    The output is a diff between the specified YAML files. For example:

    ...
 CHANGES
=========
authenticator:
- AllowAllAuthenticator
+ com.datastax.bdp.cassandra.auth.DseAuthenticator

authorizer:
- AllowAllAuthorizer
+ com.datastax.bdp.cassandra.auth.DseAuthorizer

roles_validity_in_ms:
- 2000
+ 120000
...

  6. Make sure the catalina.properties and context.xml files are present in the Apache Tomcat® conf directory.

    DSE won’t start after the upgrade if these files are missing.

    The default location of the Tomcat conf directory depends on the type of installation:

    • Package installations: /etc/dse/tomcat/conf

    • Tarball installations: INSTALL_DIRECTORY/resources/tomcat/conf

  7. Start the node:

  8. Verify that the upgraded datacenter names match the datacenter names in the keyspace schema definition.

    This is only relevant when using NetworkTopologyStrategy.

    1. Get the node’s datacenter name:

      nodetool status | grep "Datacenter"

    2. Get the replication configuration for a keyspace:

      cqlsh --execute "DESCRIBE KEYSPACE keyspace-name;" | grep "replication"

    3. If the datacenter name in replication does not match the node’s datacenter name, alter or recreate the keyspace accordingly:

      ALTER KEYSPACE keyspace-name WITH replication = {'class': 'NetworkTopologyStrategy', 'datacenter-name': '3'};

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

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

    If the default log location returns no results, check dse-env.sh for custom log locations.

    Warnings, errors, and exceptions are frequently found in the logs when starting an upgraded node. Some messages provide information to help you complete specific upgrade steps, and some messages can be ignored while the cluster is in a partially upgraded state. If you find warnings, errors, or exceptions that are unexpected or persist after upgrading the entire cluster, contact IBM Support.

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

Post-upgrade steps

The post-upgrade steps include multi-node and cross-datacenter operations that can cause errors while a cluster is in a partially upgraded state. For example, repairs can propagate incompatible data between mixed-version nodes, and SSTable snapshots can be corrupted or unreadable due to mixed SSTable formats and versions.

Only start the post-upgrade steps after you upgrade all dependent nodes. Node dependencies are determined by your deployment architecture:

Architecture Examples Post-upgrade path

Isolated or non-production deployment

  • Upgrading a test deployment before rolling out the upgrade to production.

  • Upgrading a passive datacenter in an active-passive multi-datacenter deployment.

Start the post-upgrade steps after upgrading all nodes in the test deployment or passive datacenter.

For example, in a test deployment with two datacenters and cross-datacenter replication, you must upgrade all nodes in both datacenters before starting the post-upgrade steps.

In contrast, in a test deployment with one datacenter and no cross-datacenter connections, you must upgrade all nodes in that datacenter before starting the post-upgrade steps.

Production deployment

  • Rolling out an upgrade to an entire production cluster.

  • Upgrading a multi-datacenter deployment that has cross-datacenter replication.

Start the post-upgrade steps after upgrading all nodes included in the deployment.

For example, in a multi-datacenter deployment with cross-datacenter replication, you must upgrade all nodes in all datacenters before starting the post-upgrade steps.

Complete the post-upgrade steps progressively in the recommended order. Modify the recommended order as needed for your deployment architecture and workloads.

  1. Upgrade all SSTables again.

    Your database upgrade isn’t complete until you upgrade all SSTables.

    To avoid significant performance degradation and issues with incompatible SSTables formats, always upgrade SSTables before and after any database upgrade, including minor and patch releases.

    This process is recommended for all upgrades, and it is critical for upgrades that involve a major underlying Cassandra version change.

    On each node, run nodetool upgradesstables with the -a flag to ensure that all SSTables use the latest SSTable format and version for your current database version:

    nodetool upgradesstables -a

    DataStax recommends running the upgradesstables command on one node at a time or, when using racks, one rack at a time. Running the command on too many nodes at once can degrade performance.

    You can use the --jobs option to set the number of SSTables that upgrade simultaneously. The default setting is 2, which minimizes the impact on the cluster. Set to 0 to use all available compaction threads.

    If all SSTables are already on the latest version and format, the command returns immediately and takes no action.

  2. Migrate encrypted tables and indexes.

    Encrypted tables and indexes must be migrated after upgrading DSE.

  3. Restart any services or automated operations that you disabled before starting the upgrade.

    For more information, see Avoid certain operations during the upgrade.

Lock DSE package versions

After upgrading a DSE package installation, you can prevent unintended upgrades by locking the package version:

Yum

  1. Install yum-versionlock if it isn’t already installed:

    sudo yum install yum-versionlock

  2. Lock the current DSE version:

    sudo yum versionlock dse-*

  3. When you need to allow an upgrade, clear the version lock:

    sudo yum versionlock clear
APT

  1. Use apt-mark to hold the dse package at the current version:

    sudo apt-mark hold dse-*

  2. When you need to allow an upgrade, remove the hold:

    sudo apt-mark unhold dse-*

See also

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