Oracle Database 11g Oracle Real Application Clusters Handbook, 2nd Edition, 2nd Edition

Cache Fusion II or Write/Write Cache Fusion

The CR server addressed read/write contention in the first phase of Cache Fusion. The second phase of Cache Fusion, introduced in Oracle 9i, implements the framework for current block transfers for write/write contention. Prior to Oracle 9i, whenever an instance needed to modify a data block that had been recently modified by another instance, the following sequence of operations would take place, as illustrated in Figure 12-4:

FIGURE 12-4 Write/write contention in pre–Cache Fusion

1. An instance sends a message to the lock manager requesting an exclusive lock on the block.

2. Following are the possibilities ...