This illustration shows the System Global Areas (SGA) of two instances, one on Node one and another on Node 2. Both SGAs show background procsesses such as LGWR and DBWR. The Global Cache Service (GCS) is also shown interacting with the LCK process locally, and the GCS of the other instance remotely. Both instances shared a single database. The SGA of node one is transfering blocks directly into the SGA of Node 2. This is the breakthrough technology of Cache Fusion as depicted by a large arrow.