The image shows three boxes:

• Initial state (True Caches are available)
  • Read-write data flows back and forth between applications 1 and 2 and the primary database.
  • Read-only data flows back and forth between applications 1 and 2 and True Cache 1, which is preferred.
  • No data flows to True Cache 2, but it is available.
• Preferred True Cache unavailable
  • Read-write data flows back and forth between applications 1 and 2 and the primary database.
  • Read-only data flows back and forth between applications 1 and 2 and True Cache 2, which is available but not preferred.
  • No data flows to True Cache 1, even though it is preferred, because it is unavailable.
• Both True Caches unavailable
  • Read-write and read-only data flow back and forth between applications 1 and 2 and the primary database.
  • No data flows to True Cache 1 and 2 because they are unavailable.