The PowerCenter Integration Service launches the DTM process. The DTM allocates buffer memory to the session based on the DTM Buffer Size setting in the session properties. By default, the PowerCenter Integration Service calculates the size of the buffer memory and the buffer block size.

The DTM divides the memory into buffer blocks as configured in the Buffer Block Size setting in the session properties. The reader, transformation, and writer threads use buffer blocks to move data from sources and to targets.

You may want to configure the buffer memory and buffer block size manually. In Unicode mode, the PowerCenter Integration Service uses double bytes to move characters, so increasing buffer memory might improve session performance.

If the DTM cannot allocate the configured amount of buffer memory for the session, the session cannot initialize. Informatica recommends you allocate no more than 1 GB for DTM buffer memory.