(NOTE: I don't use the guest agent at all doing provisioning.. I only use vCO / vRO for all activities, so take what I say with a grain of salt, since the guagent isn't my area of expertise)
I don't think there's a way to do this without using a (very) custom Day 2 operation.... through vCO. There's a few things working against you:
1) The built-in IaaS reconfiguration task doesn't support formatting automatically / natively. This is, in part (again, to the best of my recollection) because the guest agent is not kept on the server beyond when the initial provisioning action takes place. I can't imagine what sort of load having an agent like that running, at scale, constantly checking in for new things to do, would do to the provisioning infrastructure.
2) Taking #1 at face value as being correct, the only way (that I know of) to add Day 2 operations is through Orchestrator. But this gets a little odd because now you need to delve into the guest operations API, which requires an administrative credential... which means that you either need to have the requester pass that particular value through (which means ASD) or you need to have a consistent / known credential that can be used for a fixed Day 2 operation. And, actually, since the Day 2 reconfiguration action for disks does not include the ability to pass in the custom properties for the disk, you'd need to use ASD for that, as well.
That's the long and short of it.. I've pondered how to deal with this for quite some time, but the reality is.... there just isn't always a (simple) way to automate everything for every scenario like that, unfortunately.
-Steve
