Global Cache Statistics

Global cache statistics are accounted for across the cluster level. Like a well-audited financial statement, all the numbers for blocks served from the source instance should be equal to the blocks received at the target instance(s). The statistics also include blocks lost and blocks retransmitted during failures. In the following sections we will take a close look at the most common Oracle RAC–related system statistics and their significance in analyzing performance issues.

gc current blocks received

This statistic represents the number of current blocks received through the interconnect from other instances. This counter is incremented by a foreground or background process when a request for a current block or a “global cache cr request” results in the shipping of a current block at the other instance. On the other side, the sender increments the “gc current blocks served” statistic.