Oracle Error Message
ORA-15025: could not open disk “string”
Reason for the Error
The specified disk could not be opened. If the database instance is running as an Operating System (OS) user different from that of the ASM instance, then the permissions on the database oracle binary may be incorrect.
Solution
Check the additional error messages, if any. If the database instance is running as an OS user different from that of the ASM instance, use the “srvctl” command to stop and restart the database to fix the permissions.