I'm currently managing 7 VMs in one subscription and want to reorganize them by moving 2 of them to NewSubscriptionA and another 2 to NewSubscriptionB. The remaining 3 VMs will stay put. The goal is to simplify the billing process so that my accounting team can handle invoices without needing monthly breakdowns from me. However, I'm facing a challenge since all 7 VMs are in the same virtual network (vNet) and I've read that to transfer VMs to a new subscription, the entire vNet and its dependent resources must also be moved. This makes my situation a bit complicated. What's the best approach to achieve my goal without disrupting everything? Also, keep in mind that all my VMs are being backed up with Azure Backup.
2 Answers
It's worth noting that Azure Backup provides support for Cross Subscription Restore (CSR), but there are some caveats. For example, if your VMs are set up for Trusted Launch, you'll hit a wall there since CSR isn’t available for those instances. There’s a specific error you might encounter if you try: it clearly states that restoring Trusted Launch VMs across subscriptions isn’t supported, so keep that in mind! You might need to use the same subscription if those VMs are tagged with Trusted Launch.
I had to do something similar a while back for a project. Here’s how we handled it: First, we took snapshots of all the disks. You can create the snapshots in the specific subscriptions or move them afterward. Next, we made new disks from those snapshots and created VMs from the OS disks, attaching any necessary data disks afterward. Just a heads up: ensure the VMs and their disks are in the same availability zone for them to attach properly during the "Create VM from Disk" process. As for the vNets, if you need to move to another subscription, you might have to set up new vNets. You can also dissociate public IPs and reassign them as needed. And if they need to communicate with each other, vNet peering could be an option!
Oh man, I didn’t even consider the vNet thing. I really don't want to set up new vNets since it adds unnecessary complexity and costs. Unfortunately, splitting the VMs means I might just have to abandon this plan altogether.
That’s a bummer! I saw conflicting info in different articles about CSR, and now I'm not sure what’s true. The one talks about CSR but doesn’t specify Trusted Launch as a problem, while the troubleshooting guide says it is. I guess I’ll just have to stick with one subscription for the restore.