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The Linux kernel has traditionally not provided a raw interface, for a number of reasons. The use of raw device has been depreciated since RHEL 5 or kernel 2.6 and applications should use o_direct instead.
Raw I/O is not always a performance boost since raw I/O operations are usually synchronous, meaning the write system call cannot return until the operation is complete. See the following link:
support rawdevices by linux oracle.
There is no need to create raw devices for Oracle 10.2.0.2 or later. The filesystemio_options parameter specifies how Oracle will perform disk I/O. DIRECTIO= Direct I/O, ASYNCH=Asynchronous I/O and SETALL=both.
LVM configurations are not recommended by Oracle because they create a duplication of functionality. Oracle also does not recommended using LVMs for mirroring because ASM already provides mirroring.
When using ASM avoid using a LVM because an LVM would be redundant. However, thereare situations where certain multipathing or third party cluster solutions require an LVM. In these situations, use the LVM to represent a single LUN without striping or mirroring to minimize the performance impact.