ALTER SYSTEM CHECK DATAFILES

看联机文档的时候，看到了这么一条命令：ALTER SYSTEM CHECK DATAFILES

便记下来，以备后用。

If you add a data file to a disk that other instances cannot access, then verification fails. Verification also fails if instances access different copies
of the same data file. If verification fails for any instance, then diagnose and fix the problem. Then run the 

ALTER SYSTEM CHECK DATAFILES

 statement
on each instance to verify data file access.

当我们给rac环境添加数据文件时候，如果有其他节点无法访问到新添加的数据文件，这个时候可以通过在每个节点上执行命令：ALTER SYSTEM CHECK DATAFILES;来解决这个问题。