10 VMware Cluster Best Practices

A VMware cluster is a group of ESXi hosts that are managed as a single entity. A cluster can improve the performance, availability, and scalability of your VMware environment.

In this article, we will discuss 10 best practices for configuring and managing VMware clusters. By following these best practices, you can improve the performance, availability, and scalability of your VMware environment.

1. Use the latest VMware version

Newer versions of VMware often include important security patches and bug fixes. Additionally, new versions usually offer performance improvements and additional features that can make managing a cluster easier.

Of course, upgrading to a new version of VMware can sometimes be disruptive, so it’s important to plan the upgrade carefully. Make sure to test the new version in a non-production environment before rolling it out to your production clusters.

2. Create a cluster with an even number of hosts

If you have an odd number of hosts in a cluster and one host fails, the entire cluster is at risk because it can no longer tolerate any more failures. With an even number of hosts, however, the cluster can still function if one host fails because there are an equal number of working hosts to take its place.

This best practice is especially important in high-availability clusters where uptime is critical. By using an even number of hosts, you can be sure that your cluster will be able to withstand any single point of failure.

3. Enable DRS and HA on your clusters

DRS is a key feature of vSphere that helps to optimize and balance resource utilization across your environment. By enabling DRS on your clusters, you can automatically distribute virtual machines (VMs) and workloads across the available resources in the cluster based on defined rules and policies. This helps to improve overall performance and prevent any one VM from monopolizing resources and causing contention.

HA is another key feature of vSphere that provides high availability for VMs by restarting them on other hosts in the cluster in the event of a host failure. This helps to ensure that your applications and services remain up and running even in the event of hardware failures.

Enabling both DRS and HA on your VMware clusters will help to optimize performance and provide increased availability for your VMs.

4. Use VM-Host affinity rules to control VM placement

When you have a lot of VMs running on a cluster, it can be difficult to keep track of which VM is running on which host. This can lead to problems if you need to shut down a host for maintenance or if there’s a problem with a particular host.

VM-Host affinity rules allow you to specify which VMs should run on which hosts. This way, you can ensure that critical VMs are always running on the best hosts, and you can avoid any potential problems that might occur if VMs are randomly placed on hosts.

To set up VM-Host affinity rules, go to the vSphere web client and navigate to the cluster. Then, click the Configure tab and select VM-Host Affinity Rules.

5. Use Datastore Clusters for storage management

Datastore Clusters allow you to manage multiple datastores as a single entity, which makes it much easier to keep track of your storage usage and capacity. In addition, Datastore Clusters provide many other benefits, such as increased performance and availability, and the ability to easily add or remove datastores from the cluster without affecting the others.

Overall, using Datastore Clusters is a great way to improve the efficiency of your VMware cluster and make it simpler to manage your storage.

6. Disable vMotion, Storage vMotion, and Fault Tolerance logging on production datastores

vMotion is a process that allows you to move a running virtual machine from one host to another with no downtime. Storage vMotion allows you to move the disk files associated with a virtual machine from one datastore to another while the VM is running. And Fault Tolerance is a feature that creates a duplicate VM on another host in the cluster so that if the primary VM fails, the secondary VM takes over with no downtime.

All of these features are great for making sure your VMs are always available, but they can also be a performance drag on your production datastores. That’s because every time a VM is moved, the disk files have to be copied over to the new location. This can cause contention and slow down your storage subsystem.

The best way to avoid this problem is to disable vMotion, Storage vMotion, and Fault Tolerance logging on your production datastores. You can still use these features on other datastores, just not on the ones where performance is critical.

7. Keep up to date with security patches

As new vulnerabilities are discovered, the VMware team works hard to address them with security patches. By keeping your cluster up to date, you can be sure that any newly discovered vulnerabilities have been patched, and your environment is as secure as possible.

Additionally, many of these security patches include bug fixes and performance improvements. So, by keeping your cluster up to date, you can also enjoy the benefits of these enhancements.

8. Use Distributed Resource Scheduler (DRS) Affinity Rules to keep VMs together or apart

DRS Affinity Rules allow you to specify which VMs should or should not be placed on the same host. This can be useful for a number of reasons, such as performance (you may want to keep certain VMs together for performance reasons), licensing (you may need to keep certain VMs apart for licensing reasons), or even just for organizational purposes.

Creating DRS Affinity Rules is easy, and there are a few different ways to do it. You can use the vSphere Web Client, the vSphere Client, or even PowerCLI.

Once you’ve created your DRS Affinity Rule, you’ll need to add it to a DRS Cluster. To do this, simply edit the settings of the DRS Cluster and add the rule.

Now, when DRS runs, it will take into account your DRS Affinity Rule and place VMs accordingly.

9. Set EVC mode to match the oldest CPU in your cluster

When you set the EVC mode to match the oldest CPU in your cluster, it ensures that all hosts in the cluster are compatible with that CPU. This is important because it means that any host can be used to run any VM in the cluster, without the need for special compatibility settings.

It also means that if you need to add a new host to the cluster, you can simply use any host that has a compatible CPU. This is much simpler than having to check compatibility settings and make sure that the new host meets all of the requirements for running the VMs in the cluster.

Finally, setting the EVC mode to match the oldest CPU in your cluster ensures that you can always downgrade the CPU in your cluster if necessary. This can be useful if you need to reduce costs or if you find that a newer CPU is not compatible with some of your older applications.

10. Use Host Profiles to ensure consistent configuration across all hosts

When you have multiple hosts in a cluster, it’s important to make sure that they are all configured the same way. This ensures that there are no compatibility issues between the hosts, and that all of the hosts will work together correctly.

Host Profiles is a feature in VMware that allows you to create a template for configuring hosts. You can then apply this template to all of the hosts in your cluster, ensuring that they are all configured the same way.

This is an important best practice because it helps to avoid problems caused by mismatched configurations. It also makes it easier to manage your cluster, since you only need to update the configuration in one place (the Host Profile).