Large I/O effectiveness

“Large I/O Effectiveness” helps you to determine the performance benefits of large I/O. It compares the number of pages that were brought into cache by a large I/O to the number of pages actually referenced while in the cache. If the percentage for “Pages by Lrg I/O Used” is low, it means that few of the pages brought into cache are being accessed by queries. Investigate the individual caches to determine the source of the problem. Use optdiag to check the value for “Large I/O Efficiency” for each table and index.