"Live migration" refers to how Compute Engine transparently migrates a VM to another physical host [1]. Disk and memory is copied over, and they have some ridiculous technology that keeps network connections alive and re-attaches them to the new VM when it's been switched over, so that it causes, in principle, zero disruptions. This is much more magical than other providers, such as AWS and DigitalOcean, where such a migration results in a reboot.

You can run PostgreSQL on a VM just fine. You just have to manage itself. Cloud SQL comes with some upsides (zero management, spectacular HA failover capabilities) and some downsides (lack of extensions, lives on a separate network, no control over maintenance window); you have to decide what you're willing to live with.

You can set the upgrade window, but it can't be predicted. What you can control is the order — e.g. set your staging instance to "early" and production instance to "late", then hopefully staging should be upgraded first and you'll know ahead of the production upgrade if any issues arose.

[1] https://cloud.google.com/compute/docs/instances/live-migrati...

GCP has the best compute, storage, and networking of all the clouds. They are cheaper, faster, more scalable and more reliable than the others. Their managed services leave a lot to be desired (beta status, non-standard interfaces, and other limits) but if you're just looking to run VMs then that is the perfect fit for their cloud.

We consolidated everything on GKE now which lets use use VMs but still have the kubernetes control plane looking after things for us which has been great so far.

Maintenance windows are set for the cluster, not single instances. We were distributed across 3 AZs and Google had no suggestions for mitigating the ~5 minutes of downtime we were seeing every week or two.

The whole experience was so amateur and unprofessional it really soured me on GCE. They do have some cool tech but it seems like their cloud division needs to mature a bit.