Can I change a GCE VM instance type on the fly?

Question

I'm working with Google Compute Engine and to test it I created a small instance type which isn't very powerful. Now I want to change it to a more powerful CPU but can't seem to figure out how to do that.

Is it possible to change the instance type of a running VM?

Answer 1

You can't change the instance type of a running instance, so you'll have to shut it down and start a new one.

If you used a persistent root disk, you can reuse that disk on your replacement instance. If you used a scratch disk though, you'll have to make sure you back up your changes first.

Answer 2

In December 2013, Compute Engine was promoted to v1 (General Availability). Some notes to hopefully save folks time:

• Scratch disks are deprecated. By default boot disks are now created as persistent.

• Before you delete the old instance, save off its settings for easy reference when creating the new one:

  gcutil getinstance instance-name
  

• The disk name to use later for addinstance is the last part of the disk.source setting.

• If the disk.autoDelete setting is True, set it to False to preserve the disk:

  gcutil setinstancediskautodelete instance-name --auto_delete=False
  

• Safely delete the old instance:

  gcutil deleteinstance instance-name
  

• To create a new instance using the old instance's persistent disk as the boot disk, you need to specify the boot flag, e.g. using gcutil:

  gcutil addinstance --disk=instance-disk-name,mode=rw,boot [...]
  

  Otherwise it complains that the disk already exists and fails the instance creation.