This issue was fixed in system firmware 9.5.2.g.
If the miniroot volume is missing in a system, the property /System/Open_Problems shows Cooling in the list of affected subsystems:
-> show /System/Open_Problems
Open Problems (1)
Date/Time Subsystems Component
------------------------ ------------------ ------------
Sat Aug 29 22:29:17 2015 System, Cooling /System (Host System)
The ILOM Mini-Root system is missing. (Probability:100,
UUID:ce6e7e97-523c-e55b-a6fc-96dd2dd09187, Resource:/SYS/SP, Part
Number:9999999294, Serial Number:465769T+1520BUR294, Reference
Document:http://support.oracle.com/msg/ILOM-8000-9W)Cooling should not appear in the Subsystems column because the miniroot volume has nothing to do with the cooling subsytem.
If the miniroot volume is missing from the system, this Cooling message can be safely ignored. In addition, there is no interruption in service.