看看concepts中关于controfile的内容
contorlfile主要包含以下内容：
Among other things, a control file contains information such as:
■ The database name
■ The timestamp of database creation
■ The names and locations of associated datafiles and redo log files
■ Tablespace information
■ Datafile offline ranges
■ The log history
■ Archived log information
■ Backup set and backup piece information
■ Backup datafile and redo log information
■ Datafile copy information
■ The current log sequence number
■ Checkpoint information
可以看到，后续控制文件增长，最可能的的就是备份信息部分了
