How do we reduce disk I/O in UNIX? There are three generally accepted techniques for the DBA to reduce disk I/O:
1-Tune SQL statements to retrieve data with a minimum of disk I/O - This is generally performed by finding large-table full-table scans and replacing the full-table scan with an index scan.
2- Change the Oracle SGA - When we increase the shared_pool_size, large_pool_size, or db_cache_size, the resulting performance improvement is related to the reduction in disk I/O.
3-Reorganize tables to reduce disk I/O – This is done by selectively moving tables to tablespaces with a different blocksize, and re-sequencing table rows into the primary key