Looking at Storage Volumes under Provisioning on the Appliance tab you find a red status next to a Volume Name. If you hover your mouse over the red status you will see the message "Not valid."
This is caused when disk configurations do not align with data in the ApplianceProvisioningConfiguration.xml files. Misaligned data can be caused by:
NOTE: Changing data in the file will not break anything. The only affect of misaligned information is a red status on some volumes. Editing the xml file can be complicated, so please open a Service Request for assistance if needed.