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Solution

  • General

Type

  • Document

Level

  • Overview

Category

  • Feature Brief

Technology

  • Compute
  • SDDC

Feature Brief: Custom CPU Core Count

Introduction

The Custom CPU Core Count capability allows you to select a reduced number of CPU cores to run per host, with respect to the default number of cores for the host type.  The extra cores are disabled logically and are not visible to the host hypervisor software.

This feature is designed to help avoid a situation of running servers with underutilized CPU capacity.  It can also potentially reduce the costs for running mission-critical applications licensed on a per core basis.  For example, when running heavy database applications, such as Oracle or MS SQL Server, you run out of memory or storage much faster than out of CPU. Not only does that leave you with the underutilized CPU capacity, but also you pay higher licensing costs as compared with a better sized host. For a more detailed example, see Oracle on VMware Cloud on AWS – Custom CPU Core Count.

Setting CPU Core Count

The following table shows the default number of cores for various host types, and the options available for a reduced core count

Host Type

Default Physical Cores

Custom Core Options

i3

36

8, 16

i3en

48

4, 8

 

The number of cores must be specified at the time of cluster creation. 

  1. Go to the VMware Cloud on AWS console
  2. Click on your SDDC, and select the “Add Cluster” action
  3. Under the section “Cluster to Be Added” you will see that you can specify the Number of CPU Cores Per Host. Select the value that works best for your workloads and finish the action.

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Additionally, please take note of the informational alert in the blue box.

  • Changing the number of cores does not affect the price of the host.
  • After the cluster is added, you cannot change the number of cores.

SDDC Considerations

The number of cores per CPU that you select applies to all the hosts in that cluster at the time of deployment. Other clusters within the SDDC are not affected. If any hosts are added to the cluster, or used to replace a failed host, it will use the same core count as with the other hosts.

Furthermore, this customization cannot be applied to the first cluster in an SDDC, but only subsequent clusters that you add.

Keep in mind that reducing core count affects the compute performance of all workloads on the host and could lead to system performance degradation. For example, vCenter and vSAN overhead can become more noticeable, and operations like adding clusters and hosts may take longer to complete.

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