vShere Cluster Power down and Maintenance mode

[azuser]

We have a cluster with ten ESXi hosts, and we need to power down the cluster where vCenter is running. I understand that we should put all ESXi hosts into maintenance mode and then power them down through the DCUI.

In the past, I experienced an issue where an ESXi host did not exit maintenance mode when using the GUI. I was able to SSH into the host and run the CLI command to exit maintenance mode successfully.

In this situation, I will put all the ESXi hosts into maintenance mode. I will first go to the ESXi host where vCenter is running, power it down, and then when the host comes back up, vCenter should start automatically. If the ESXi host does not exit maintenance mode, I plan to SSH into it and use the CLI to bring it out. If the CLI also fails, I might be in trouble.

My questions are:

1. Is it possible for an ESXi host to get stuck in maintenance mode?

2. If that happens, is it safe to power down the ESXi host without putting it into maintenance mode first? I'm just trying to understand the worst-case scenario.

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[ninjabrum]

1. Yes, though this is not normal and you should fix the host issue.  I run hundreds of hosts and patch regularly.  I haven't had a host NOT exit MM in years.  Entering MM is another story - VM affinity rules, vm overrides, and many other things can prevent the host from entering MM.  Again, you should know which rules to disable during maintenance or discover what is preventing the host from entering MM.

2.  Maybe.  Maybe not.  In vCenter 8, you won't see the vCLS VM's needed for cluster services - vCenter 7, you can see them.  Those may take a little longer for vCenter to move / destroy. Make sure there are zero VM's or vCLS appliances before you manually shut down the host.  You should try restarting host services to see if you can get it to go into MM or out of MM.

maintenance mode is a basic function of ESXi hosts. If it's not working 100% of the time, you should invest the time to discover why.

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