Red Hat Engineering is currently converting the Red Hat Tuning Brief, Optimizing SAS on Red Hat Enterprise Linux (RHEL) 6 & 7 Version 1.3, to RHEL Versions 8 (optimizingsasonrhel6and7_2.pdf).
The new guidelines are expected for general distribution by the first of April, 2022.
Until that document is available, please note the following interim advice for RHEL Tuning and Configuration using RHEL 8 for SAS 9:
The majority of the configuration and tuning for RHEL 8 will follow the same RHEL 7 specific guidelines as posted in the current RHEL 6 & 7 Document. The following exceptions/notes are provided. If there are any questions/concerns about interim advice, please open a SAS Technical Support ticket for support, and liaison to the R&D CS&E Performance Team. If Red Hat support is required they will be integrated into the conversation to open a support ticket with them.
Exceptions/Notes:
- The Power Management, tuned, udev, ulimits, and multipath advice will remain the same. Please note that while the tuned files can remain in their current RHEL 7 location and still function, the official ongoing default location for RHEL 8 tuned files will change.
- The IO Elevator selections that default in RHEL 8 are the Same recommended in RHEL 6 & 7, but have undergone Name Changes:
- The DEADLINE elevator recommended for use in RHEL 6 & 7 for non-FLASH IO devices, is now called the mq-deadline elevator, and is still recommended.
- The NOOP elevator recommended for use in RHEL 6 & 7 for FLASH IO Devices, is now called the none elevator, and is still recommended.
- The new elevators in RHEL 8 & 9 designated as Kyber, and BFQ (replacing CFQ) are Not to be used with SAS 9 or SAS Viya.
- The advice in Section 2.3.1.1 Concatenated vs. Striped Logical Volumes, will be updated. For HDD Monolithic Storage systems it will still apply. For high speed ALL FLASH Storage systems, it is still helpful to performance to follow this advice, but please note that Single LUN LV’s can be adequately performance. This is dependent on the specific All Flash storage models used, and their ability to offer high LUN Queue depth management. I.E., in the case of VMWare, VMDKs can be mounted as single LUN LVs on high speed Flash Storage.
For the most part, you can apply the RHEL 7 advice in the RHEL 6 & 7 Tuning Guideline for RHEL 8. If you have questions on the exceptions above, please file a Technical Support Ticket to engage the R&D CS&E Performance Team for guidance.
The RHEL 7 Tuning advice for SAS 9 is largely acceptable for SAS Viya Hosts. Please note that this advice will apply largely to the Viya Worker and Runtime Environment (Compute) nodes. Some of the advice may vary for Microservices and Controller nodes – please see your Account Team or Technical Support for any implementation specific guidelines for your planned workload.
