Integer 

Dynamic. Scope = ALTER SYSTEM ... DEFERRED. 

64 

Operating system dependent 

DB_FILE_DIRECT_IO_COUNT specifies the buffer size (in number of blocks) used for I/O operations performed by backup, restore, or direct path read and write functions. The I/O buffer size is a product of DB_FILE_DIRECT_IO_COUNT * DB_BLOCK_SIZE. Assuming a block size of 2048, the resulting buffer size is 128K. The I/O buffer size cannot exceed the maximum size of an I/O operation for your platform.

Assigning a high value to this parameter results in greater use of PGA and SGA memory. 

Note: If you have previously used the CCF_IO_SIZE parameter and are migrating to DB_FILE_DIRECT_IO_COUNT, remember that CCF_IO_SIZE was specified in bytes while DB_FILE_DIRECT_IO_COUNT must be specified in database blocks. 

See Also: Oracle8i Designing and Tuning for Performance for more information on setting this parameter.