oracle rac cluster wait events

ServerOracle ConceptsSoftware SupportRemote Tune your SQL plan and schema for better optimization. will go into more detail when we benchmark our RAC on VMware by stress testing Oracle Database 2 Day + Real Application Clusters Guide provides complete information about monitoring performance with Oracle Enterprise Manager, including: Automatic Database Diagnostic Monitor and Oracle RAC Performance. This is because a global operation on the buffer is pending and the operation has not yet completed. . waits desc (idle events last), Event Waits Timeouts Time (s) might have a slow private interconnect. Coughs, colds, sore throats, flu and most fevers. Deleting some of the hot rows and re-inserting them back into the table may alleviate the problem. NON-RAC environment. Monitoring can include such things as: Notification if there are any VIP relocations, Status of the Oracle Clusterware on each node of the cluster using information obtained through the Cluster Verification Utility (cluvfy), Notification if node applications (nodeapps) start or stop, Notification of issues in the Oracle Clusterware alert log for OCR, voting disk issues (if any), and node evictions. In an excerpt of the AWR report below, I'm seeing several wait events with "Cluster" as the wait class in a RAC environment with 5 nodes and whose version is 11gR2. local to the machine (the remote node), need to access these buffer caches event_id, event order by 3; Note: instance received the block after a remote instance The amount of the data is directly related to the work being performed, rather than the number of sessions allowed on the system. Usually, either interconnect or load issues or SQL execution against a large shared working set can be found to be the root cause. Oracle RAC is somewhat of a unique case of an Oracle environment, but everything learned about wait events in the single instance database also applies to clustered databases. blocks were shipped without having been busy, pinned, or. The tasks can vary from 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. Fri, Feb 17, 2023 6:00 AM PST. @. retry 27 27 0 0 4.5, gcs remote Anyone The Interconnects page shows the public and private interfaces on the cluster and the load contributed by database instances on the interconnect, including: Overall throughput across the private interconnect, Notification if a database instance is using public interface due to misconfiguration, Throughput and errors (if any) on the interconnect, Throughput contributed by individual instances on the interconnect. feedback. Oracle forum. Both Oracle Enterprise Manager Database Control and Oracle Enterprise Manager Grid Control are cluster-aware and provide a central console to manage your cluster database. to collect additional RAC specific data: Note: 135714.1 Script to Collect RAC Diagnostic Information (racdiag.sql) The output of the script has tips for how to read the output. request 820 113 154 188 136.7, global cache null to This section describes how to monitor GCS performance by identifying data blocks and objects which are frequently used (hot) by all instances. 5.0, global cache open 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. If this time is long, When you log in to Oracle Enterprise Manager using a client browser, the Cluster Database Home page appears where you can monitor the status of both Oracle Clusterware and the Oracle RAC environments. Oracle forum. Cache fusion interconnect, load write 141 0 1 4 23.5, enqueue Waits such as SQL*Net waits and any The Oracle of maintains consistency throughout the RAC with lock mastering and resource Guided Meditation. What are the differences in Oracle RAC wait events? risk as it already may have happened by another node. Oracle technology is changing and we Contact Geek DBA Team, via email. Oracle Enterprise Manager accumulates data over specified periods of time, called collection-based data. Plus, you can see the details about SQL/sessions by going to a prior point in time by moving the slider on the chart. 1. Your vendor-specific interconnect documentation for more information about adjusting IPC buffer sizes, Oracle Clusterware Administration and Deployment Guide for more information about enabling and using the OIFCFG and OCRDUMP utilities. Ion any instance. Oracle 20 million people rely on AmericanTowns each year to find & share local information. ASH statistics that are gathered over a specified duration can be put into ASH reports. The advisory will also identify the busy objects and SQL highest cluster wait time. Excel-DB, Oracle RAC Understanding the internals will help us understand it even performance. SupportApps skip prepare failure 37 0.1 6.2, global lock Oracle Enterprise Manager 13.5.0.13 download available on My Oracle Support. The contention-oriented wait event statistics indicate that a block was received which was pinned by a session on another node, was deferred because a change had not yet been flushed to disk or because of high concurrency, and therefore could not be shipped immediately. Events that start with "ges%' are related to Global Enqueue Services. The ASH report Top Cluster Events section is part of the Top Events report that is specific to Oracle RAC. In other word, they have to do with waits experienced in shipping current or consistent-read versions of blocks across instances in a RAC cluster, Events that start with ges% are related to Global Enqueue Services, gc current block 2-way - Indicates that a current block was sent from either the resource master requiring 1 message and 1 transfer. Wait Events for Database. Scripting on this page enhances content navigation, but does not change the content in any way. set linesize 200 set pages 55 col sid format 99999 col name format a36 col p1 format 999999999 Head 'P1' col program format a25 col p2 format 999999999 Head 'P2' col p3 format 999999999 Head 'P3' col pgm format a15 head 'What' col state format a15 col wt format 9999999 head 'Wait|Time' col WaitEvent format a38 head 'Wait Event' col lc format 99999999999.99 head 'last call' select A.sid, decode(A.event,'null event','CPU Exec',A.event) WaitEvent, A.p1,A.p2,A.p3, decode(A.state,'WAITING','WTG', 'WAITED UNKNOWN TIME','UNK', 'WAITED SHORT TIME','WST', 'WAITED KNOWN TIME','WKT') wait_type, decode(A.state,'WAITING',A.seconds_in_wait, 'WAITED UNKNOWN TIME',-999, 'WAITED SHORT TIME',A.wait_time, 'WAITED KNOWN TIME',A.WAIT_TIME) wt, round((last_call_et/60),2) lc, substr(nvl(b.module,b.program),1,15) pgm from v$session_wait A, v$session B where 1=1 and (A.event like 'gc%' or A.event like 'GC%' or A.event like 'ge%') and A.event not like '%remote message' and A.event not like '%sleep' and A.sid=B.sid and B.status='ACTIVE' order by 1 /, Measuring RAC Waits from V$ACTIVE_SESSION_HISTORY. In Oracle RAC environments, each AWR snapshot captures data from all active instances in the cluster. Please abide by the Oracle Community guidelines and refrain from posting any customer or personally identifiable information (PI/CI). removed from this listing. Each instance has a set of instance-specific views, which are prefixed with V$. _FAIRNESS_THRESHOLD value then the lock might be downgraded. Storage Details: ZFS appliance Storage. current block pin ti 12 0.0 2.0, global cache Two node RAC cluster. Setting it to FALSE will disable it. c 17 0 0 0 2.8, db file parallel Oracle RAC Statistics and Events in AWR and Statspack Reports, Monitoring Performance by Analyzing GCS and GES Statistics, Analyzing Cache Fusion Transfer Impact Using GCS Statistics, Analyzing Response Times Based on Wait Events. Wait Time desc, Waits desc, Instance We use the clustering for active/passive failover. the normal system enqueues. gets 183 0.4 30.5, global cache I made a career switch, emigrated, learned a new language and moved into the IT industry starting 2000. However, the special use of a global buffer cache in RAC makes it imperative to monitor inter-instance communication via the cluster-specific wait events such as gc cr request and gc buffer busy. AWR does not store data that is aggregated from across the entire cluster. Focus on the buffer cache and its operations. Waiting for blocks to arrive may constitute a significant portion of the response time, in the same way that reading from disk could increase the block access delays, only that cache fusion transfers in most cases are faster than disk access latencies. The aggregates are provided on the pages where the activity data is presented including: Database Performance Page, Top Activity Page, Wait Details Page and Service Details Page. The non-RAC related ones have been Top 10 Foreground Events by Total Wait Time ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tota Wait % DB In a typical scenario the requesting node will The views expressed on these pages are mine and learnt from other blogs and bloggers and to enhance and support the DBA community and this web blog does not represent the thoughts, intentions, plans or strategies of my current employer nor the Oracle and its affiliates. e-mail: Burleson Consulting Monitoring an Oracle RAC database often means monitoring this situation and the amount of requests going back and forth over the RAC interconnect. snap_id between nnn and nnn+1and will request the resource master for shared access to that block. Chart for Global Cache Block Access Latency: Each cluster database instance has its own buffer cache in its System Global Area (SGA). In the following Load wait event tuning in RAC: Load Oracle Database Performance Tuning Guide for information about AWR and ADDM, Oracle Database 2 Day + Real Application Clusters Guide for more information about how to access and analyze global and local ADDM data using Oracle Enterprise Manager, Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_ADVISOR and DBMS_ADDM packages. Events that start with GCS% and gc% are Cache Fusion-related waits. 29 0 1 18 4.8, library cache because every time a user connects to your application, a resource is allocated Can any one please suggest an alernative strategy that we can follow to resolve this issue. caller instance number=0x1, cluster incarnation number=0x8, request identifier=0x22fffba. Ion "global cache cr request" wait event. These instances are running on separate hardware, with its own OS. An additional segment statistic, gc buffer busy, has been added to quickly determine the busy objects without having to query the V$SESSION_WAIT view mentioned earlier. the PCI speeds. DatabaseJournal.com publishes relevant, up-to-date and pragmatic articles on the use of database hardware and management tools and serves as a forum for professional knowledge about proprietary, open source and cloud-based databases--foundational technology for all IT systems. 2. collect the statistics and rebuild the indexes associated with the table with the same PCT free as changedto the table. indicates that the block was pinned or held up by a session event, count(*) cnt from events. wait on global cache cr request. Single Instance. In addition, Oracle Added on Dec 3 2009 Once your interconnect is operative, you cannot significantly influence its performance. The data presented is rolled up from all of the running instances. Oracle instances 697 465 0 0 116.2, global cache open Since then I have been a Sr. DBA, (Technical) Project Manager, Sr. sequential read event. current blocks recei 541 1.2 90.2, global cache This section describes frequent wait events that you should be aware of when interpreting performance data. The Oracle of The most common wait events related to this are gc cr request and gc buffer busy (note that in Oracle RAC 9i and earlier these wait events were known as "global cache cr request"and "global cache buffer busy" wait events).