On VM side, what's the difference between 1. rebooting a vm and 2. shutting down a vm and power it on shortly after?

[SLCK]

In the initial startup of a VM, there's some initialization going on before it fully powers on. I assume during a vm reboot, such things do not take place, right? I'm also curious if there are any other things (like CoW, mem cache, vcpu allocation) that are different between the two scenarios.

I'm hoping with this post someone can shed more light on this. Thank you

[DavoudTeimouri]

Actually, on VM side there is no different, just during VM power on, VM's BIOS initialize hardware same as physical machines.

But on host side, restarting VM is totally different with power off and short power on.

[SLCK]

I see. Thank you for your input.

Is there anything different on the hypervisor compared to a bare metal setup when those boot actions are taken? Thanks

[wila]

Hi,

Right, there are differences between a reboot and a shutdown and power on.

A few examples.

If you vMotion a VM to a host with a different CPU then if you inspect the CPU from within the guest it will show up with the CPU from the old host.

If you then reboot the VM it _still_ does show the old CPU, only after a shut down it will show the new CPU on the following boot.

Also (this is something I've seen on Workstation/Fusion, not sure if it is the same on vSphere) if you have a non persistent USB connection and reboot the guest, the USB connection is still there. If you shut down and restart, you have to connect the USB device again from within the user interface.

--

Wil