DATASTAX SUPPORT ALERT - January 17, 2020
**** DSE and OSS Driver functionality to be merged ****
**** Possible Performance Impact When Upgrading to RHEL 7.7 ****
If you have questions, contact DataStax Support
1: DSE and OSS Driver functionality to be merged.
Since 2016, DataStax has maintained separate DataStax Drivers for Apache Cassandra (OSS drivers) and DataStax Drivers for DataStax Enterprise (DSE drivers). Today, DataStax announced the unified DataStax drivers that merge all of the DSE drivers functionality into the existing OSS drivers. All new features for Apache Cassandra and DataStax Enterprise will be developed in the unified DataStax drivers. Bug fixes and support for DSE drivers continues until January 1st, 2022. The drivers are unified under the single, Apache License v2.0, open-source DataStax drivers.
If you are currently using the latest version of a DSE driver, specific actions are required to upgrade to the unified DataStax driver:
- A driver version change within the dependencies
- Altering your imports to match the new locations of the DSE driver functionality.
There are no changes to the API in the upgrade from the latest versions of the DSE drivers to the unified DataStax drivers other than the import locations.
As a reminder, the unified DataStax Java Driver version (4.4.0) is not binary compatible with the legacy OSS Java Driver 3.x and DSE Java Driver 1.x. There are significant API changes when moving from these legacy versions to the the unified DataStax Java Driver version. The OSS Java Driver 3.x and DSE Java Driver 1.x lines will be supported until January 1st, 2022. Plan your upgrade accordingly and follow the upgrade guide for details. Datastax recommends that any upgrade is thoroughly tested before deploying to production.
C++
Driver Artifact: cassandra-cpp-driver
Introduced in driver version: 2.15.0
Download Location: https://downloads.datastax.com/cpp-driver/
GitHub Repository: https://github.com/datastax/cpp-driver
Documentation: https://docs.datastax.com/en/developer/cpp-driver/latest/
Graph Package: N/A
Graph GitHub Repository: N/A
Upgrade Guide: https://docs.datastax.com/en/developer/cpp-driver/latest/#upgrading
C#
Driver Artifact: InstallPackage CassandraCSharpDriver
Introduced in driver version: 3.13.0
Download Location: https://www.nuget.org/packages/CassandraCSharpDriver/
GitHub Repository: https://github.com/datastax/csharp-driver
Documentation: https://docs.datastax.com/en/developer/csharp-driver/latest
Graph Package: InstallPackage CassandraCSharpDriver.Graph
Graph GitHub Repository: https://github.com/datastax/csharp-driver-graph
Upgrade Guide: https://docs.datastax.com/en/developer/csharp-driver/latest/upgrade-guide/
Java
Driver Artifact: com.datastax.oss.java-driver-core
Introduced in driver version: 4.4.0
Download Location: https://search.maven.org/search?q=com.datastax.oss
GitHub Repository: https://github.com/datastax/java-driver
Documentation: https://docs.datastax.com/en/developer/java-driver/latest
Graph Package: included in artifact above
Graph GitHub Repository: included in GitHub above
Upgrade Guide: https://docs.datastax.com/en/developer/java-driver/latest/upgrade_guide/
Node.js
Driver Artifact: npm install cassandra-driver
Introduced in driver version: 4.4.0
Download Location: https://www.npmjs.com/package/cassandra-driver
GitHub Repository: https://github.com/datastax/nodejs-driver
Documentation: https://docs.datastax.com/en/developer/nodejs-driver/latest
Graph Package: npm install cassandra-driver-graph
Graph GitHub Repository: https://github.com/datastax/nodejs-driver-graph
Upgrade Guide: https://docs.datastax.com/en/developer/nodejs-driver/latest/upgrade-guide/
Python
Driver Artifact: pip install cassandra-driver
Introduced in driver version: 3.21.0
Download Location: https://pypi.org/project/cassandra-driver/
GitHub Repository: https://github.com/datastax/python-driver
Documentation: https://docs.datastax.com/en/developer/python-driver/latest
Graph Package: pip install cassandra-driver[graph]
Graph GitHub Repository: included in GitHub above
Upgrade Guide: https://docs.datastax.com/en/developer/python-driver/latest/upgrading/
See https://www.datastax.com/blog/2020/01/better-drivers-for-cassandra for the public announcement of unified DataStax drivers.
2: Possible Performance Impact When Upgrading to RHEL 7.7
RHEL 7.7 has passed functional testing and is a supported release for the use of DSE. However, testing did identify that in some cases there can be some performance differences compared to earlier releases. See Controlling the Performance Impact of Microcode and Security Patches for CVE-2017-5754 CVE-2017-5715 and CVE-2017-5753 using Red Hat Enterprise LinuxTunables for details and the option to disable the protection mechanism to recover lost performance.
As described in a previous DataStax blog post Impact of Meltdown Patches to DSE Performance Datastax Support recommends specific performance testing of an application before upgrading your operating system.
For all operating system upgrades, the following settings can have a significant impact on cluster performance. It is important to ensure that all test clusters use appropriate settings for the following:
- Disk settings are optimized for Recommended production settings. Read-ahead specifically has a significant impact.
- Ensure that no governors are used to lower the CPU Frequency. See this DataStax Support KB article to verify that CPU scaling is set to "performance".
- When appropriate, ensure disk_access_mode in cassandra.yaml is set to mmap_index-only.
DataStax has not reviewed the RHEL 7.7 multiple-queue I/O scheduling mechanism for block devices which is in technical preview https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/pdf/7.7_release_notes/Red_Hat_Enterprise_Linux-7-7.7_Release_Notes-en-US.pdf - Search for (BZ#1109348)
If you have questions or concerns, contact DataStax Support by opening a ticket in the DataStax Support Portal.
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