gc buffer busy wait
GC Buffer Busy Wait Fix in Oracle RAC Here’s the thing with gc buffer busy wait in Oracle RAC — it usually points to contention on data blocks that are being shared across RAC nodes. When one instance is holding a block in a mode another instance needs, the second waits, causing this event to spike. Let’s break down how to fix it: Identify the hot block or object causing contention Run a query on v$session_wait or gv$session_wait to see which objects or blocks are involved. Often, it’s a segment or index that many sessions hit simultaneously. Check the type of contention Is it on data blocks (DML), index blocks, or undo segments? That guides your action. Common fixes: Application tuning : Are many sessions updating the same rows or blocks? Try to spread the workload to reduce "hot spots." For example, avoid sequences that generate contention on the same block, or tune application logic to avoid frequent updates ...