Understanding Esxi Maintenance mode and Standyby mode

[Wajeeh]

Dear All,

I would like to understand about maintenance mode, for example I've two hosts in a cluster and I need to perform firmware upgrade on Host A. Now before I do that I must migrate the virtual machine to Host B, So now Host A is free. Now I can right away turn off the Host A and start firmware upgrade procedure OR first I should say for this host to enter maintenance mode and then turn off ?

Second I want to have clear understanding of standby mode ? Can I also put a host in Standby mode for firmware upgrade or other maintenance activities ?

thanks,

[MKguy]

You should always put hosts into maintenance mode when you do reboots, firmware updates, apply ESXi updates (most patches require the host to be in maintenance mode) or anything like that. This will make sure all processes on the host are properly prepared, no VM will be (accidentally/DRS) migrated onto the host again, the HA agent is disabled etc.

Standby mode is a totally different thing and only applies only if you use DPM. For power-saving purposes, it will aggregate VMs on a number of hosts and shut down the ones not running any ("Standby mode"), powering them up dynamically via WOL or IPMI/ILO/DRAC if the workload on your cluster increases and you need more resources to cope with the demand.

You probably aren't going to use DPM, but here is more info on how it works:

VMware Distributed Power Management: Concepts and Usage

[a_p_]

What you usually do is to select a host end select "Enter Maintenance Mode" before you (or DRS if it's licensed and enabled) start to migrate VMs. This is to ensure no other VMs can be powered on or migrated to this host while you migrate the VMs, and that you can verify that everything is ok after the update before you put the host back into production. Once done and the Enter Maintenance Mode task has finished, you can safely shut down or reboot the host.

Standby Mode is something different and used with DPM (Distributed Power Management) which shuts down unnecessary hosts in times of low usage to save energy.

André

[Wajeeh]

Hello Andre,

Ok, for standby mode , I am clear.

For Maintenance mode your are saying that as a First Step, I should put a host to maintenance prior migrating the virtual machines from it to other available hosts ? Then when all the virtual machines are moved, host will be in maintenance mode and I can turn it off and hand over to support engineer for firmware activity during which host will be rebooted to complete the process. Once support engineer task is done, I bring the host back out of maintenance mode and resume normal operation, right ?

[a_p_]

Yes, exactly.

When you click Enter Maintenance Mode, the host will not go into maintenance mode right away, but just start this task. The host will only enter maintenance mode once all VMs are moved.

André

[Wajeeh]

Hello Andre,

So, clicking 'enter maintenance mode' just initiates the task, and if I don't have any DRS, I will have chance to move all my virtual machines myself to desired places , right ? Once host is empty it will complete the task and will be pushed to maintenance mode completely ?

thanks,

[a_p_]

Yes, that's how it works. Unless you have DRS in place, you need to either manually migrate (vMotion) powered on VMs or shut them down.

André

[Shrikant_Gavhan]

Hi Wajeeh,

You can not put ESXi to maintenance mode untill you move all the powered on machines elsewhere, or shut them down. ESXi might not respond the maintenance mode oeration if performed in this situation.

If you are performing patching or upgrade via Update manager then you can not perform any of these operations if the ESXi is not in maintenance mode.

VMware vSphere 4 - ESX and vCenter Server

above link for your reference.

Thanks and Regards,

Shrikant Gavhane

[BruceBannermanz]

An ESXi host that is running and has working VMs on it, when placed into maintenance mode, starts vmotioning those machines to another host in the cluster, using DRS, and will not enter maintenance mode until all VMs are moved. The only reason that you would have to manually power down any VMs is if you do not have DRS enabled.

Using Maintenance Mode

You place a host in maintenance mode when you need to service it, for example, to install more memory. A host enters or leaves maintenance mode only as the result of a user request.

Virtual machines that are running on a host entering maintenance mode need to be migrated to another host (either manually or automatically by DRS) or shut down. The host is in a state of Entering Maintenance Mode until all running virtual machines are powered down or migrated to different hosts. You cannot power on virtual machines or migrate virtual machines to a host entering maintenance mode.

When no more running virtual machines are on the host, the host’s icon changes to include under maintenance and the host’s Summary panel indicates the new state. While in maintenance mode, the host does not allow you to deploy or power on a virtual machine.

VMware vSphere 4 - ESX and vCenter Server

Message was edited by: BruceBannermanz