Oracle SuperCluster: osc-setcoremem simulator

Target Audience: Oracle SuperCluster customers and Oracle technical support

• Is it possible to use setcoremem to achieve my desired configuration?
• Why setcoremem is behaving differently than the way I expected it to be?
• Why can't I add more memory to a particular domain?

.. are some of the common/recurring questions that I've heard in the last several years. Unfortunately in most cases questions like "Is it possible to use setcoremem to achieve my desired configuration?" won't arise until after the customer had their hands on the SuperCluster configuration they ordered. If the customer has a way of figuring out what combinations of core/memory configurations are possible in the planned SuperCluster configuration beforehand, it'd help them tremendously in planning; and likely minimize frustrations and service requests later on if the tool shows different possible combinations than the ones they'd prefer.

To address some of the questions and concerns that are similar to the ones mentioned above, osc-setcoremem simulator was introduced in SuperCluster Exafamily update 2.4.x. The self-contained osc-setcoremem binary from Exafamily update 2.4.x can be used to run simulations on any SPARC hardware not necessarily on SuperCluster SPARC hardware alone as long as the target SPARC hardware has Solaris 11 or later running. While normal execution (non-simulation) of osc-setcoremem requires root privileges to make the intended core/memory configuration changes in one or more logical domains (LDoms), it is not necessary to use root privileges to run the simulator. In other words, normal users with limited privileges can run osc-setcoremem on any SPARC hardware including non-SuperCluster hardware to simulate the behavior of osc-setcoremem on a variety of SuperCluster T4/T5/M6/M7/M8 supported configurations such as fully/half/quarter populated configurations.

Few things to keep in mind:

• Simulator functionality was embedded in the Exafamily osc-setcoremem utility. Same self-contained osc-setcoremem executable binary can be used to simulate in addition to reconfiguring core and memory of one or more logical domains on a live SuperCluster.

• On non-SuperCluster SPARC hardware, osc-setcoremem runs in simulation mode by default. On SuperCluster nodes, normal execution (non-simulation) is the default. Simulation mode can be enabled by setting the shell variable SSC_SCM_SIMULATE to any value before invoking osc-setcoremem.

• It is unlikely that the simulator will answer or address all questions and concerns that customers might have. The main objective of the simulator is to provide some insight into the behavior of the utility (what works and what doesn't) by simulating the SuperCluster configuration that the customer is planning to deploy or already have access to. The main advantage is that the customers do not need to have the actual hardware in their data centers before they can plan and finalize their domain configurations.

• Even though some additional information is shown in simulation mode such as the resource distribution among locality groups, the utility won't show anything much descriptive during simulations so it is still up to the user to run multiple simulations to understand the tool behavior and to figure out what works and what does not.

We will explore the simulator in the next few blog posts. Meanwhile please check the official documentation pages out at Configuring CPU and Memory Resources (osc-setcoremem) and Run a Simulation to learn more about the functionality of osc-setcoremem and for the instructions to run the simulator.

ALSO SEE:

1. osc-setcoremem: A Brief Introduction
2. Non-Interactive osc-setcoremem

(To be continued ..)