Raw devices are disk partitions or logical volumes that have not been formatted with a file system. When you use raw devices for database file storage, Oracle writes data directly to the partition or volume, bypassing the operating system file system layer. For this reason, you can sometimes achieve performance gains by using raw devices. However, because raw devices can be difficult to create and administer, and because the performance gains over modern file systems are minimal, Oracle recommends that you choose Automatic Storage Management or file system storage in preference to raw devices.

 其实Oracle 对RAW 支持还是不够，所以才认为RAW device 难创建和管理。如果是SA 兼DBA 的话，就不会出现Oracle 官方所担心的问题了。所以DBA 必须要对SA 只是要有多点的认识，不然在方案选择方面就比较局限。