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MargaretC
SAS Employee

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:

 

  1. 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.
  2. The IO Elevator selections that default in RHEL 8 are the Same recommended in RHEL 6 & 7, but have undergone Name Changes:
    1. 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.
    2. The NOOP elevator recommended for use in RHEL 6 & 7 for FLASH IO Devices, is now called the none elevator, and is still recommended.
    3. 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.
  3. 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.  

6 REPLIES 6
FK1
Lapis Lazuli | Level 10 FK1
Lapis Lazuli | Level 10

Hello @MargaretC ,

do you have any updated information regarding the new guidelines? You wrote that they were expected for general distribution by the first of April, 2022. 

Sincerely yours,

FK1

MargaretC
SAS Employee

Unfortunately not.   Red Hat is producing this paper and they are currently working a couple of issues with new versions of RHEL and GFS2.  

 

I will post the updated information on this channel when it is available.

FK1
Lapis Lazuli | Level 10 FK1
Lapis Lazuli | Level 10

Hello @MargaretC ,

I was wondering whether you had gained any new information regarding the topic of RHEL 8 Tuning Guidelines since your last post in June 2022?

Sincerely yours,

FK1

MargaretC
SAS Employee

The information in this post seems to be all that is needed to make SAS run optimally on RHEL 8.

David-H
SAS Employee
Hi @MargaretC!

Do you know if this info is also valid for RHEL 9?
MargaretC
SAS Employee
David -H,

Yes, The same guidelines will apply to RHEL 9. There will be an update we are finishing now to this document for the RHEL Swappiness Algorithm. The default was changed from 10 to 60 in RHEL 8. You will need to follow the advice in this post to change it back:


* Swappiness Algorithm - General Setting - Change in swap behavior between RHEL 7 and RHEL 8 kernels - Red Hat Customer Portal<> (Setting should be changed from 60 to 10. Note - if you are running the Throughput Performance tuned profile, you do not need to change the global setting mentioned in this post, it is governed in the profile. )

* Swappiness Algorithm - Cgroups Settings https://access.redhat.com/solutions/6785021 Premature swapping while there is still plenty of pagecache to be reclaimed - Red Hat Customer Portal<> (Setting should be changed back to 1 at the Cgroup Level)

Hope this helps,



Tony Brown



Tony Brown
Distinguished Software Performance Engineer - SAS9 R&D
(he/him/his)<>
Tel: + 1 469 807 7455 ● Mobile +1 214 207 9245 ● tony.brown@sas.com
Remote ● Dallas, TX

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