"file %s is read only - cannot recover using backup control file"
*Cause: An attempt to do media recovery using a backup control file found
that one of the files is marked read only. Read only files do not
normally need to be recovered, but recovery with a backup
control file must recover all online files.
*Action: If the file really is read only, take it offline before the
recovery, and bring the read only tablespace online after the
database is open. If the file does need recovery use a control file
from the time the file was read-write. If the correct control file
is not available, use CREATE CONTROLFILE to make one.