Comment by littlestymaar
1 year ago
But that's not what's happening: they aren't keeping a full host for you.
Your argument is like saying that a bus traveler costs the gas needed to power the bus, but it's never the case: the bus would be cruising no matter what. And symmetrically the VM host would be up no matter what you did with your instance.
I'm not sure that's true. Shutting down unneeded hardware seems like a very simple but major optimization.
You assume that the hardware would be unneeded, but that's a very strong assumption.
It would be very bad for any cloud provider to leave hosts with only one VM running on it, and you can be pretty sure only very small minority of their park that end up in that situation where shutting down a single VM would lead to a shut-down of the entire host, because it means that the host was vastly under-used in the first place.
As far as I know, most cloud hosts don't actually support automatically moving live VMs, so I think it's fairly common for a host to be left running a single VM.
At least in AWS, they never supported this, and in fact may require you to reboot an instance occasionally in order for it to be moved to a new hardware host (typically when they are upgrading their hardware).
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