It's both. A yellow flag on the VM's icon and a triggered alarm.
There are two VMDK files in the datastore. The first is <servername>.VMDK, which is the size of the only disk the server has (35 GB). The other VMDK is <servername>-000002.VMDK, which is around 7 GB, which looks like a delta file to me. Snapshot Manager doesn't show any snapshots. The owner of the VM deleted the only snapshot a couple of weeks ago, so I would have expected the delta file to have been consolidated by the system, and then to disappear. I don't like that idea of just acknowledging and clearing the alarm, and leaving that <servername>-000002.VMDK file hanging out there. I wonder if I acknowledged and cleared the alarm, would I be able to safely delete the 000002.VMDK file? The VM is running fine, according to the owner.