Hyper-v Host restarts
Quick question, i have 150 windows updates waiting to be installed on each of my two Hyper-v hosts (Server 2008 R2), however i don't want to just restart them without making sure I'm doing things right. I'm fairly new to Hyper-v as i have been using VMWare in my previous position.
There isn't enough memory on either host to live migrate machines across the cluster to avoid down time (something i intend on fixing soon)
Is it safe to just restart the hosts one by one when no-one is using the system? Do i need to shut down the VM's manually before restarting the host?
Many thanks and happy halloween!
Definitely shut down the guest VMs first.
Make sure you have a decent off host backup, 150 updates is a lot to apply in a oner.
Thank-you. Just taken over at a new school and playing catchup :) I might delay the restart until another time as backup has been playing up a bit too
Very wise if you're not sure re the backup!
Good luck, have a nice evening.
May I ask what your reasoning is? In 4 years I have never shut down guest VMs before restarting a Hyper-V host. However, I've been applying updates monthly rather than doing that many in one go. Is the number of updates factoring into your recommendation?
Originally Posted by kmount
Sure, a valid question.
I guess you set your environment up yourself so you know what action is configured for the "what do I do when the host is going down" on each of your VMs, i.e guest shutdown or suspend/save state not that I'm a fan of that level of trust.
If the OP didn't set up the environment and can't be sure of the VM automatic stop configuration it would seem most logical to me to at least maintain some sort of safety in shutting down the guests.
We're also of course assuming the integration services are installed and functioning on each of the guests to actually respond to the desired action on host maintenance (and not for it to just kill it harshly)
Horses for courses I suppose, I just work on the side of caution just incase, especially on an environment I didn't build; though your post did make me wonder what others did - Is it better to save VM state or shutdown the Guest OS when restarting the host? - Spiceworks & Hyper-v shutdown scripts from host to guest
I have 1 Hyper-V host and its a nightmare when it comes to rebooting the host itself
What I tend to do is:
- Patch & reboot all the guests fully
- Run Veeam to ensure they are all backed up.
- I then power off all the guests
- I have a virtual DC, so I tell this one to automatically startup, but not the rest - this saves the Host grinding to a halt when they all start up. Plus I find that startup times vary so mcuh that the scheduled startups are ridiculously long!
- Reboot the Hyper-V host.
- Once it and the DC has restarted, manually reboot the guests, making sure my SQL Server is fully booted up and settled in before starting the next. Also due to memory constraints I dont do anymore than 2 at a time (YMMV).
In my opinion It is always best to shutdown the guest VM. Reason why is because you don't know what is being written back to the cluster and the hyper visor could become corrupted there are too many factors that could go wrong. Just because MS might say yes it's ok to do this. but in the real world do you really want to take that chance
This thread is a testament to bare metal hypervisors. Not long ago you'd have been laughed at for suggesting piles of updates to your host!
If you migrate the VM's to another host before rebooting then you can reboot the fine. Assuming your cluster quorum settings can sustain one failure, if not then the whole cluster will forcibly shut down anyway (done that)