Since we released our NUMA metrics dashboard, hundreds of customers were able to detect issues and unbalances NUMA usage. The performance degradation due to NUMA remote node usage can be massive and easily reach 75% performance loss.

VMware NUMA issue

We also get many questions about vNUMA and how to configure NUMA the best way. Therefore, we start a series about NUMA, vNUMA with this article. 

How to activate VMware vNUMA with lower CPU count

What is NUMA

Non-uniform memory access (NUMA) is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to the processor. Under NUMA, a processor can access its own local memory faster than non-local memory (memory local to another processor or memory shared between processors). The benefits of NUMA are limited to particular workloads, notably on servers where the data is often associated strongly with certain tasks or users. Wikipedia —

When it comes to vNUMA, it means, that VMware ESXi is showing the physical NUMA configuration of the underlying hardware to the virtual machine, instead of hiding it. 

You can read more about NUMA, vNUMA and Performance issues here:

vNUMA is deactivated by default for virtual machines with less than 9 vCPUs, or CPU or Memory hot-add is activated.

vNUMA controls

VMware offers a bunch of advanced parameters to tweak vNUMA that can be found here:

Activate vNUMA for VMs with less vCPUs cores (i. e. 4, 6 or 8 vCPUs)

The virtual machine must be powered off to proceed.

edit virtual machine hardware and settings

Deactivate Hot Plug

First make sure, that CPU hot add or hot plug are deactivated.

NUMA deactivate CPU-Hot-Plug

Same for Memory Hot Plug

NUMA memory hot plug

Now we change the VM options

Edit VM options

Change the NUMA option

Please keep in mind, that most advanced NUMA options are not existing in the list, so you need to add them. If the option is already in the list, you can just change the value and save the config.

add NUMA configuration parameter

add the parameter numa.vcpu.min 

As the NUMA architecture will only be present with 9 and more vCPUs by default, you should set the value to the current amount of vCPUs, i. e. if you have 2 vCPU sockets and 2 vCPU cores each, you should set the value to 4.

NUMA minimal setting

After powering on the virtual machine the guest operating system can see the NUMA architecture and act accordingly.

Please be aware, that the VMware VMkernel does a pretty good job in managing NUMA, but sometimes and especially if you find systems that have NUMA unbalanced, it makes sense to give vNUMA the preference.

Metrics and Logs

(formerly, Opvizor Performance Analyzer)

VMware vSphere & Cloud

Monitor and Analyze Performance and Log files:
Performance monitoring for your systems and applications with log analysis (tamperproof using immudb) and license compliance (RedHat, Oracle, SAP and more) in one virtual appliance!

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Use Case - Tamper-resistant Clinical Trials


Blockchain PoCs were unsuccessful due to complexity and lack of developers.

Still the goal of data immutability as well as client verification is a crucial. Furthermore, the system needs to be easy to use and operate (allowing backup, maintenance windows aso.).


immudb is running in different datacenters across the globe. All clinical trial information is stored in immudb either as transactions or the pdf documents as a whole.

Having that single source of truth with versioned, timestamped, and cryptographically verifiable records, enables a whole new way of transparency and trust.

Use Case - Finance


Store the source data, the decision and the rule base for financial support from governments timestamped, verifiable.

A very important functionality is the ability to compare the historic decision (based on the past rulebase) with the rulebase at a different date. Fully cryptographic verifiable Time Travel queries are required to be able to achieve that comparison.


While the source data, rulebase and the documented decision are stored in verifiable Blobs in immudb, the transaction is stored using the relational layer of immudb.

That allows the use of immudb’s time travel capabilities to retrieve verified historic data and recalculate with the most recent rulebase.

Use Case - eCommerce and NFT marketplace


No matter if it’s an eCommerce platform or NFT marketplace, the goals are similar:

  • High amount of transactions (potentially millions a second)
  • Ability to read and write multiple records within one transaction
  • prevent overwrite or updates on transactions
  • comply with regulations (PCI, GDPR, …)


immudb is typically scaled out using Hyperscaler (i. e. AWS, Google Cloud, Microsoft Azure) distributed across the Globe. Auditors are also distributed to track the verification proof over time. Additionally, the shop or marketplace applications store immudb cryptographic state information. That high level of integrity and tamper-evidence while maintaining a very high transaction speed is key for companies to chose immudb.

Use Case - IoT Sensor Data


IoT sensor data received by devices collecting environment data needs to be stored locally in a cryptographically verifiable manner until the data is transferred to a central datacenter. The data integrity needs to be verifiable at any given point in time and while in transit.


immudb runs embedded on the IoT device itself and is consistently audited by external probes. The data transfer to audit is minimal and works even with minimum bandwidth and unreliable connections.

Whenever the IoT devices are connected to a high bandwidth, the data transfer happens to a data center (large immudb deployment) and the source and destination date integrity is fully verified.

Use Case - DevOps Evidence


CI/CD and application build logs need to be stored auditable and tamper-evident.
A very high Performance is required as the system should not slow down any build process.
Scalability is key as billions of artifacts are expected within the next years.
Next to a possibility of integrity validation, data needs to be retrievable by pipeline job id or digital asset checksum.


As part of the CI/CD audit functionality, data is stored within immudb using the Key/Value functionality. Key is either the CI/CD job id (i. e. Jenkins or GitLab) or the checksum of the resulting build or container image.

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