Summary

We need to add extra test cases into test_excl.py and add tiered storage scenario.

Acceptance Criteria (Definition of Done)
There should be the following test cases:

1. Existing file; exclusive=true; same config;
2. Existing file; exclusive=false; same config;
3. Existing file; exclusive=true; different config;
4. Existing file; exclusive=false; different config;
5. Nonexisting file; exclusive=true;
6. Nonexisting file; exclusive=false;