MAXLOGHISTORY :
This parameter is useful only if you are using Oracle in ARCHIVELOG mode with Real Application Clusters. Specify the maximum number of archived redo log files for automatic media recovery Real Application Clusters. Oracle uses this value to determine how much space in the control file to allocate for the names of archived redo log files. The minimum value is 0. The default value is a multiple of the MAXINSTANCES value and depends on your operating system. The maximum value is limited only by the maximum size of the control file.
仅当使用RAC，并且数据库处于归档模式时有用。

MAXDATAFILES :
Specify the initial sizing of the datafiles section of the control file at CREATE DATABASE or CREATE CONTROLFILE time. An attempt to add a file whose number is greater than MAXDATAFILES, but less than or equal to DB_FILES, causes the Oracle control file to expand automatically so that the datafiles section can accommodate more files.
The number of datafiles accessible to your instance is also limited by the initialization parameter DB_FILES.
指定创建数据库时控制文件中关于数据文件部分的初始大小。