IBM BPM, V8.0.1, All platforms > Tuning > Advanced tuning > Database: general tuning
Avoid double buffering
Because the database attempts to keep frequently accessed data in memory, in most cases there is no benefit to using file system caching. In fact, performance typically improves by using direct input/output (I/O), when files read by the database bypass the file system cache and only one copy of the data is held in memory. This allows more memory to be given to the database and avoids memory overruns in the file system as it manages its cache.
A further advantage can be gained on some operating systems such as AIX by using concurrent I/O. This bypasses per-file locking, shifting responsibility for concurrency control to the database, and in some cases, allowing more useful work to be offered to the adapter or the device.
An important exception to this guideline occurs for large objects (such as LOB, BLOB, and CLOB), which are not buffered by the database itself. In this case, it can be advantageous to arrange for file system caching, preferably only for files that back large objects.