I saw an interesting question today from Robert Kloosterhuis in the private vExpert App Modernization Slack Channel who working with vSphere with Tanzu using NSX Advanced Load Balancer (NSX-ALB) and wanted to know if it was possible to deploy NSX-ALB with just a single Service Engine (SE)?
The default behavior of NSX-ALB is to deploy two SE for availability purpose but for testing and/or homelab usage, it could certainly help with resources and time to spin up an environment using NSX-ALB. I was also curious if this was possible and reached out to NSX-ALB Engineering team and within a few minutes, I got a response that not only was this possible to do but pretty easy to configure.
To modify this default behavior, we need to update the Service Engine group prior to SE VMs being deployed. To do so, login to NSX-ALB UI and under Infrastructure->Service Engine Group and then click on the Advanced tab and change the default Buffer Service Engines value of 1 to 0 which will will have NSX-ALB deploy just a single SE VM rather than the default two.
To confirm that our NSX-ALB have been configured correctly, I have enabled vSphere with Tanzu using NSX-ALB and as you can see from the screenshot below, only a single SE VM has been deployed rather than the default behavior of two SE.
Note that this tip only applies if you're using the Enterprise or higher-tier license, since the Essentials edition is limited to the Legacy Active/Passive model, and this requires the N+M (buffer) service engine model.