[p0rkbelly]

Who needs nested virtualization when you have bare metal?

VM Migration is only for maintenance on GCP -- and customers can't control it, just Google.

AWS can hot patch live systems in place without any downtime, so, that's better than a migration (which has a brown out / maintenance period)

[JoshTriplett]

> Who needs nested virtualization when you have bare metal?

AWS's non-bare-metal systems can boot in ~10s with enough tuning.

Their bare-metal systems take tens of minutes to boot.

Nested virtualization would allow scaling up and starting new nodes much faster.

[p0rkbelly]

If you have a use case for spinning up nodes fast -- what is the use for nested virtualization? Sounds like that should be containers on any underlying single-virtualized layer?

[JoshTriplett]

Sometimes you want the safer isolation of virtualization, and you want to spin up individual workload elements in virtual machines.

[boulos]

Disclosure: I worked on nested virtualization for GCE.

Even when you offer bare metal, it’s actually still nice to have nested virt! Otherwise, every node has to be a full sized host. So when you have a K8s cluster or similar with a pile of nodes and want to allow some teams to use it (e.g., Android emulator, firecracker, whatever), it’s really nice not to have to say “okay, this group requires full bare metal hosts that they manage themselves”.

tl;dr: nested virt is still a nice to have so that all your infrastructure looks the same.

Edit: Also, you can trigger migration yourself if you want (gcloud compute instances simulate-maintenance-event), but that's mostly to convince yourself that nothing bad will happen.