You are managing a policy-managed three-instance RAC database. You ran database ADDM for the datatabase and noticed gc current block congested and gc cr block congested waits.
What are two possible reasons for these wait events?
A.
The wait events indicate a delay in processing has occurred in the Global Cache Services (GCS),which is usually caused by high load.
B.
The wait times indicate that the blocks must wait after initiating a gc block request, for the round trip from the start of the wait until the blocks arrive.
C.
The wait events indicate that there is block contention resulting in multiple requests for access to local blocks.
D.
The wait events indicate that the local instance making the request for current or consistent read blocks was waiting for logical I/O from its own buffer cache at the same time.
The load-oriented wait events indicate that a delay in processing has occurred in the GCS, which is usually caused by high load, CPU saturation and would have to be solved by additional CPUs, load-balancing, off loading processing to different times or a new cluster node.For the events mentioned, the wait time encompasses the entire round trip from the time a session starts to wait after initiating a block request until the block arrives.