Miscellaneous Oracle RAC wait events

Miscellaneous Oracle RAC wait events 1. gc remaster : resource remastering happens based on 2 situation : 1.When Instance leaves or joins cluster. 2.Dynamic remastering from a less busy instance to an instance where demand for that object is too high.This is also called resource affinity. 2. gc cr grant busy : The gc cr […]

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Oracle RAC Cache Fusion

Cache Fusion is one of the most Important concepts in Oracle RAC. As we know each and every instance of RAC cluster is having its own local buffer cache where it does cache functionality.But when multiple users are connected to different nodes , a need to access or lock a data block owned by other […]

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How GRD works in Oracle RAC

An Oracle RAC database has the same processes and memory structures as a single instance.Oracle database have additional process and memory structures that are specific to Oracle RAC.The global cache service and global enqueue service processes, and the global resource directory (GRD) collaborate to enable cache fusion. Global Resource Directory [GRD] : Cluster operations require […]

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Contention-Related Wait Events

Contention-Related Wait Events : It is common to see the gc cr block busy and gc current block busy wait events in Oracle RAC systems. These events occur when a consistent read or current block is needed from another instance yet it is taking some time to receive that block, and the sending of the […]

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Load-oriented oracle rac wait events

Load-oriented oracle RAC wait events : 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, […]

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Message-Oriented Oracle RAC wait events

Message-Oriented Oracle RAC wait event The message-oriented wait event statistics indicate that no block was received because it was not cached in any instance. Instead, a global grant was given, enabling the requesting instance to read the block from disk or modify it. If the local instance is the resource master, the grant happens immediately.If […]

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Grouping Oracle Rac Wait Events

To determine the amount of work and cost related to inter-instance messaging and contention, examine block transfer rates, remote requests made by each transaction, the number and time waited for global cache events as described under The response time for cache fusion transfers is determined by the messaging and processing times imposed by the physical […]

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Block-Related Oracle Rac Wait Events – Part 2

An event can be anything that Oracle has to perform on behalf of a set of instructions sent by the user interface. The term “wait” is used because every time a user connects to your application, a resource is allocated to perform tasks on its behalf. The waiting comes when a session is waiting for […]

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Block-Related Oracle Rac Wait Events – Part 1

The block-related wait event statistics indicate that a block was received as either the result of a 2-way or a 3-way message, that is, the block was sent from either the resource master requiring 1 message and 1 transfer, or was forwarded to a third node from which it was sent, requiring 2 messages and […]

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Basic on Oracle RAC wait events

Analyzing and interpreting what causes sessions to wait is an important method to determine where time is spent. In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. For example, when a session on an instance is looking for a block in the global cache, it […]

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