How Does Exadata Smart Flash Cache Determine What Is Cached?

Exadata Storage Server Software makes intelligent decisions on what data to cache in the Exadata Smart Flash Cache. When data is read as part of a SQL operation, the Exadata Storage Server Software checks to see if the data is likely to be accessed again and if the data is not part of a large scan. The Exadata Smart Flash Cache does not cache the results of large I/O operations, since this would end up pushing a lot of data out of the cache as it added the scan results to it. If the data does not fit this profile and the data is not a large object, the data block is placed into the Exadata Smart Flash Cache.

The Exadata Storage Server Software will also cache data from some modify operations. Once the write to the log file is confirmed, allowing the write operation to complete, the block can be considered for addition to the Exadata Smart Flash Cache. The Exadata Storage Server Software is smart enough to know to eliminate some types of writes from consideration, such as writes for backups, mirroring operations, Data Pump operations, ASM rebalances, and the like.