RAC Wait Event: "gc current block 2 way" & "gc current block 3 way"

Block oriented waits are the most common wait events in the cluster wait events. The block oriented wait event statistics indicate that the requested block was served from the other instances. In a two – node cluster environment a message is transferred to the current holder of the block and holder ships the block to the requestor. In a cluster environment with more than two nodes, the request for the block is sent to the holder of the block through the resource master and includes an additional message.

 

The average wait time and total wait time should be considered when being alerted to performance issues where these particular waits have a high impact. Usually, either interconnects or load issues of SQL execution against a large shared working ser can be found the root cause. The following are the most common block oriented waits

gc current block 2 – way ( 2 Node RAC Environment)

gc current block 3 – way ( 3 or More  Node RAC Environment )

Pictorial Description of the steps involved in the above wait events in exclusive mode and shared mode.

gc current block 2 – way ( Exclusive Mode)

gc current block 2 – way ( Shared Mode)

gc current block 3 – way ( Exclusive Mode)

 

gc current block 3 – way ( Shared Mode)