Nutanix Controller Virtual Machine (CVM) maintenance mode is the topic i’ll cover in this quick blog post. Reason being i have been asked about this a few times recently.
First – Yes – CVM and hypervisor maintenance mode are two different things.
Hypervisor maintenance mode means no virtual machines (VMs) will run on the hypervisor host and CVM maintenance mode means the CVM will not participate in the Nutanix cluster and e.g. will not serve IO to the VMs running on the hypervisor host where the CVM is running or for any remote VMs.
Before we start i’ll just cover two useful commands to check CVM process and service status which are:
- genesis status – CVM specific
- cluster status – Cluster wide
When i run genesis status in one of my CVMs i get the following output.
You can see that all apart from three processes/services listed has one or more process IDs (PID) associated with it. In addition to just run genesis status which gives you a one time output from the command you can run watch genesis status and this will give you the same output plus that the output will update every 2 seconds. This is useful during debug and various other cases.
When i run cluster status i’ll get information about the Nutanix cluster including all the CVMs. The following figure list the output for my local CVM only but apart from including same information for all CVMs in the cluster you’ll also get information about all CVM IPs, the Cluster state and if Lockdown mode is enabled or not.
However – the easiest way to check status of your cluster is going into the Prism UI:)
Back to CVM maintenance mode. When AOS is being upgraded and hypervisors are being upgraded the CVMs are put in maintenance mode one after another so there is not many reason you would wanna do it manually so i’ll just present how it looks when a CVM is in maintenance mode.
Command “genesis status” shows:
Command “Cluster status” shows the following for the CVM in maintenance mode
Command “ncli host ls” includes:
Prism UI shows:
When back to normal Prism UI shows (as usual during normal production)
