The hit rate when accessing the data cache is too low. For a balanced database application, the hit rate should not be less than 99%, as otherwise too much data would have to physically be read. Hit rates may be temporarily low such as when reading a table for the first time, or when a tablescan is repeated and the table does not fit into 10% of the data cache (only for _LRU_FOR_SCAN =YES). The 15-minute average data cache hit rate should not be less than 99%.

In addition to increasing the data cache (watch out for paging problems in the operating system), you should also determine the cause of the high number of reads.

Single SQL statements are often a main cause of the total number of logical and physical reads. Increasing the cache only transfers the load from the hard disk to the CPU, although an additional index can turn a read-intensive table search into a less-intensive direct access.