Read-only Tablespaces Recovery Issues
Backup Control File
If you have a read-only tablespace on read-only media, then you may encounter errors or poor
performance when recovering with the USING BACKUP CONTROLFILE option.
Backup Control File (continued)
This situation occurs when the backup control file indicates that a tablespace was read/write
when the control file was backed up. In this case, media recovery may attempt to write to the
files. For read-only media, the database issues an error saying that it cannot write to the files.
红色标注的部分，我很是纳闷，有点想不通。这句到底什么意思呢？
难道只读表空间备份的时候，控制文件将其看成读写表空间进行备份？
