I have several datastore clusters in my service offerings. Is there a way to automate the VM placement based on the size of the VM?

For example, if the service offering contains a VM with less than 500 GB of storage then it will be deployed on STORAGE_POOL_1 but if is configured with 500 GB or more storage it will automatically, without any manual selection or runtime changes by the user, be deployed on STORAGE_POOL_2. I thought there is a way to do this -- I would almost even swear that I have done this before -- but I cannot find or remember how to do this.