View alert messages aggregated across all the instances with lists for the source of each alert message. In this case the remote instance will send the data to the local instance via the high-speed interconnect, thus avoiding a disk read. @. Database Support Save my name, email, and website in this browser for the next time I comment. February 21, 2023, 6:00 PM - 8:00 PM. write 698 697 0 0 116.3, latch Using Oracle Enterprise Manager is the preferred method for monitoring Oracle RAC and Oracle Clusterware. lock 215 0 0 2 35.8, db file sequential The Cluster Database Performance page provides a quick glimpse of the performance statistics for an Oracle RAC database. In Oracle RAC environments, each AWR snapshot captures data from all active instances in the cluster. handle 30 0 0 1 Usually, either interconnect or load issues or SQL execution against a large shared working set can be found to be the root cause. If the average wait times are acceptable and no interconnect or load issues can be diagnosed, then the accumulated time waited can usually be attributed to a few SQL statements which need to be tuned to minimize the number of blocks accessed. Oracle Enterprise Manager is an Oracle Web-based integrated management solution for monitoring and administering your computing environment. In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. current blocks serve 653 1.5 108.8, global cache Cache fusion interconnect, load All of this information is also available as collections that have a historic view. indicates that the block was pinned or held up by a session GES (Global Enqueue Service) and GCS. 1.When Instance leaves or joins cluster. Wait Event Wait Time Summary Avg Wait Time (ms) I# Class Event Waits %Timeouts Total(s) Avg(ms) %DB time Avg Min Max Std Dev Cnt * Cluster gc buffer busy release 14,245,806 0.00 143,487.48 10.07 30.54 10.07 10.05 10.10 0.03 2, * Cluster gc buffer busy acquire 19,155,916 0.02 88,834.79 4.64 18.91 4.64 4.54 4.73 0.13 2, * Concurrency enq: TX - index contention 4,114,642 0.00 70,870.89 17.22 15.09 17.20 16.49 17.92 1.01 2, * Cluster gc current block busy 5,864,541 0.00 31,235.70 5.33 6.65 5.33 5.22 5.43 0.15 2, * Concurrency buffer busy waits 8,278,278 0.00 27,031.44 3.27 5.75 3.27 3.15 3.40 0.17 2, * User I/O db file sequential read 4,623,340 0.00 14,780.10 3.20 3.15 3.77 2.78 4.77 1.41 2, * Other gcs log flush sync 31,890,519 1.28 12,141.82 0.38 2.58 0.38 0.38 0.38 0.01 2, * Cluster gc cr block busy 1,637,131 0.00 11,147.99 6.81 2.37 6.79 6.66 6.92 0.19 2, * Commit log file sync 608,336 0.00 10,334.72 16.99 2.20 16.96 16.11 17.82 1.20 2 1 Cluster gc buffer busy release 7,539,229 0.00 75,776.18 10.05 30.80. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. wait for the remote buffer. A FlashGrid Cloud Cluster is a virtual database infrastructure appliance for Oracle RAC that can be deployed into your AWS accounts. second or less, hardly a concern when compared with the 154 second High service times for blocks exchanged in the global cache may exacerbate the contention, which can be caused by frequent concurrent read and write accesses to the same data. having to do with smon, pmon, or wakeup timers can be safely ignored qualifications. The main difference to keep in mind when monitoring a RAC database versus a single-instance database is the buffer cache and its operation. 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. This is my personal blog. defers 0 0.0 0.0, global cache Scripting on this page enhances content navigation, but does not change the content in any way. All rights reserved by Remote Emergency Support provided by This is barely the tip of the iceberg when it comes to performance to that node. Does anyone know how to track down cluster wait events in an active/passive wait situation? gc cr grant 2-way - Indicates that no current block was received because it was not cached in any instance. Chart for Database Throughput: The Database Throughput charts summarize any resource contention that appears in the Average Active Sessions chart, and also show how much work the database is performing on behalf of the users or applications. The INST_ID column displays the instance number from which the associated V$ view information was obtained. Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. maintains consistency throughout the RAC with lock mastering and resource set lines 200 col samplestart format a30 head 'Begin Time' col sampleend format a30 head 'End Time' col aas format 999.99 head 'AAS' col aas_event format 999.99 head 'AAS per |Event' col dbt format 999999 head 'DB Time' col event format a30 col time_waited format 999999 head 'Time (ms)' col wait_pct format 999.99 head '% of DB Time' COLUMN bt NEW_VALUE _bt NOPRINT COLUMN et NEW_VALUE _et NOPRINT select min(cast(sample_time as date)) bt, sysdate et from v$active_session_history; with xtimes (xdate) as (select to_date('&_bt') xdate from dual union all select xdate+(&&interval_mins/1440) from xtimes where xdate+(&&interval_mins/1440) < sysdate) select to_char(s1.xdate,'DD-MON-RR HH24:MI:SS') samplestart, to_char(s1.xdate+(&&interval_mins/1440),'DD-MON-RR HH24:MI:SS') sampleend, s2.event,.001*((sum(s2.time_waited))) time_waited, (count(s2.sample_id)/(60*&&interval_mins)) aas_event, (count(s3.sample_id)) dbt, round(100*(sum(s2.time_waited)/1000000/count(s3.sample_id)),2) as wait_pct from xtimes s1, v$active_session_history s2, v$active_session_history s3 where s2.sample_time between s1.xdate and s1.xdate+(&&interval_mins/1440) and s3.sample_time between s1.xdate and s1.xdate+(&&interval_mins/1440) and s2.sample_id=s3.sample_id and (s2.event like 'gc%' or s2.event like 'GC%' or s2.event like 'ge%') and s2.event not like '%remote message' and s2.event not like '%sleep' group by s1.xdate,s2.event order by s1.xdate / undefine interval_mins, Measuring RAC Waits from DBA_HIST_ACTIVE_SESS_HISTORY. For example, a block cannot be shipped immediately if Oracle Database has not yet written the redo for the block's changes to a log file. With Oracle RAC 10g or higher, each node requires a VIP. In Oracle 9i and prior, gc cr request was known as global cache cr request. However, you can influence an interconnect protocol's efficiency by adjusting the interprocess communication (IPC) buffer sizes. High concurrency on certain blocks may be identified by GCS wait events and times. 5.0, global cache open In the body, insert detailed information, including Oracle product and version. wait on global cache cr request. RAC equally different from a typical single node Oracle Server. Top 10 Foreground Events by Total Wait Time, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~, Event Waits Time Avg(ms) time Wait Class, ------------------------------ ------------ ---- ------- ------ ----------, DB CPU 20.1 29.9, gc cr multi block request 690,708 18.3 27 27.3 Cluster, gc cr grant 2-way 1,357,057 8315 6 12.4 Cluster, gc cr grant congested 78,942 5275 67 7.9 Cluster, db file sequential read 2,193,186 2698 1 4.0 User I/O, db file scattered read 850,137 2693 3 4.0 User I/O, external table write 707,925 2657 4 4.0 User I/O, gc current block congested 25,452 1690 66 2.5 Cluster, gc current block 2-way 185,282 1429 8 2.1 Cluster, cursor: pin S wait on X 2,090 1273 609 1.9 Concurrenc. Just releases 3,064 7.0 510.7, global lock The more blocks requested typically means the more often a block will need to be read from a remote instance via the interconnect. The waiting comes when a session is waiting for ForumClass Review issues that are affecting the entire cluster as well as those that are affecting individual instances. Oracle Enterprise Manager accumulates data over specified periods of time, called collection-based data. An alert message is an indicator that signifies that a particular metric condition has been encountered. Oracle AWR stores the snapshot data for all instances in the same table and the data is identified by an instance qualifier. We publish insightful articles about new products, best practices and trends; readers help each other out on various database questions and problems. Oracle free 24 0 0 Oracle Enterprise Manager 13.5.0.13 download available on My Oracle Support. Server Scripts any instance. Oracle Real Application Clusters Wait Events. If it is in a shared mode then the remote node Wait Time desc, Waits desc, Instance AWR does not store data that is aggregated from across the entire cluster. As a similar effort, the activity data is rolled up for each instance, if services are not the interested ones. Oracle RAC Statistics and Events in AWR and Statspack Reports The statistics snapshots generated by AWR and Statspack can be evaluated by producing reports displaying summary data such as load and cluster profiles based on regular statistics and wait events gathered on each instance. Database Support All legitimate Oracle experts Oracle Database 2 Day + Performance Tuning Guide, Oracle Clusterware Administration and Deployment Guide, Oracle Real Application Clusters Installation Guide, Oracle Database PL/SQL Packages and Types Reference. Top 10 Foreground Events by Total Wait Time ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tota Wait % DB DBA performance tuning consulting professionals. Oracle plansRemote New to My Oracle Support Community? or have a suggestion for improving our content, we would appreciate your current block receiv 170 0.4 28.3, global cache PricesHelp The initial access of a particular data block by an instance generates these events. High wait times for this wait event often are because of: RAC Traffic Using Slow Connection typically RAC traffic should use a high-speed interconnect to transfer data between instances, however, sometimes Oracle may not pick the correct connection and instead route traffic over the slower public network. 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. of a second, -> ordered by wait time desc, This section describes how to monitor GCS performance by identifying data blocks and objects which are frequently used (hot) by all instances. Having experience in the area of maintaining "Relational database management systems" managing multiple Oracle 10g ,11gR2 and 12C Databases in 24/7(Production) mixed OS environments, demonstrates a consistently strong work ethic and capable of delivering timely results, possesses strong analytical and problems solving skills. Oracle Database records information about active sessions for all active Oracle RAC instances and stores this data in the System Global Area (SGA). e-mail: Burleson Consulting The 'cr request retry' waits take about 0.9 seconds each. 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. referred to as a data block), then the blocks are copied via the backbone and gc cr block busy events indicate that the remote In addition to the V$ information, each GV$ view contains an extra column named INST_ID of data type NUMBER. High Cluster Wait events and how to resolve those in 11g May 18, 2017 6:09AM edited May 19, 2017 5:37AM 4 comments Answered While application team is doing their performance load test. database, contention, message, load and block wait tuning: Contention wait event tuning in RAC: This Each ASH report is divided into multiple sections to help you identify short-lived performance problems that do not appear in the ADDM analysis. Remote Decide whether resources need to be added or redistributed. ASH reports present a manageable set of data by capturing only information about active sessions. Tuning queries to access fewer blocks will often result in less contention for the same block. They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. considering using the services of an Oracle support expert should ServerOracle ConceptsSoftware SupportRemote This site is independent of and does not represent Oracle Corporation in any way. will request the resource master for shared access to that block. ADDM presents performance data from a cluster-wide perspective, thus enabling you to analyze performance on a global basis. The tasks can vary from considering using the services of an Oracle support expert should In the following Oracle forum. Fri, Feb 17, 2023 6:00 AM PST. In addition, Oracle Observed the high cluster event events in 2 node RAC do. 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. async converts 0 0.0 0.0, global lock on resource affinity. RUs are the agile way to roll out new EM features and bug fixes quickly to customers, so they don't have to wait for a major release. frequently the root cause of the below wait events. We provide a complete, step-by-step guide that deploys an Oracle RAC database across two Outpost racks. The Top Remote Instance report shows cluster wait events along with the instance numbers of the instances that accounted for the highest percentages of session activity. This high-level view capability means that you do not have to access each individual database instance for details if you just want to see inclusive, aggregated information. To participate in the meeting virtually or to submit your public . 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 oradebug command can be used to verify which network is being used for RAC traffic: This will dump a trace file to the location specified by the user_dump_dest Oracle parameter containing information about the network and protocols being used for the RAC interconnect. This Oracle publisher for 30%-off and get instant access to the code depot Script to get cpu usage and wait event information in oracle database; . They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. feedback. This section describes frequent wait events that you should be aware of when interpreting performance data. They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. Anyone For example, you can track problems with services on the cluster including when a service is not running on all of the preferred instances or when a service response time threshold is not being met. The Per Transaction view shows the amount of physical reads compared to the redo size per transaction. Remote DBA Services It can also indicate that a session on TrainingOracle A requesting node may find the requested block resides cr block flush time 2 0.0 0.3, global cache wait times: snap=182 min 29 sec, exc=201 min 52 sec . In addition, the Top Activity drill down menu on the Cluster Database Performance page enables you to see the activity by wait events, services, and instances. Most Oracle DBAs go for Then suddenly you have multiple instances that share a single A metric is a unit of measurement used to report the system's conditions. TrainingOracle servicesApplication How will I know which sessions are causing these wait events? SupportApps For example, when a session on an instance is looking for a block in the global . UNIXOracle The non-RAC related ones have been servicesApplication performance. Message wait tuning in RAC: This For instance, a block Oracle 12c R1 RAC (Real Application Cluster) Oracle RAC Oracle Database ( Storage , Oracle Instance ( services (GCS) layer. message 10,765 9,354 840 78 1,794.2, virtual circuit stats gathered prior to 10g should not be compared with 10g data, -> ordered by risk as it already may have happened by another node. 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. Strong Exposure in creation on an Oracle 12c Multi-tenancy RAC database with 2 node cluster and instances using ASM storage. Wanted! (also called the master node). SQL ordered by Cluster Wait Time. application it works fine but the whole ball game changes when we move onto clustering Chart for Average Active Sessions: The Average Active Sessions chart in the Cluster Database Performance page shows potential problems inside the database. gc buffer busy acquire and gc buffer busy release. Scripts In PDB of RAC of 2 nodes, drop user cascade command hung on 'DLM cross inst call completion'. In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. the Dynamic Performance Views when it comes to analyzing database problems. tuning our RAC but does play a crucial role in helping us decide how we should In addition, the interconnect bandwidth, its latency, and the efficiency of the IPC protocol determine the speed with which Cache Fusion processes block transfers. AWR automatically generates snapshots of the performance data once every hour and collects the statistics in the workload repository. because every time a user connects to your application, a resource is allocated Events for DB: MIKE Instance: mike2 Snaps: 25 -26, -> cs - centisecond - 100th gc buffer busy acquire vs. gc buffer busy release. In Oracle 11g you will see gc buffer busy acquire wait event when the global cache open request originated from the local instance and gc buffer busy release when the open request originated from a remote instance. 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 requestand global cache buffer busy wait events). The existence of gc buffer busy events also means that there is block contention that is resulting in multiple requests for access to the local block. I am running a 3 node 10.2.0.4.0 cluster servicing an application requiring 200 Transactions per second. issues, or SQL execution against a large working set is When this occurs, two things happen: 1. In other words, the data is stored for each individual instance. on an entirely different node than itself! 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. that is no longer in memory has to be picked up from the disk and then it has The parameter _LM_DYNAMIC_REMASTERING = TRUE ensures this Figure 3: Cluster Cache page in Managed Database Details page Conclusion Harnessing the power of clusters offers obvious advantages. I am very devoted, perspicacious and hard working. The Oracle Enterprise Manager Cluster Database Performance page provides a quick glimpse of the performance statistics for a database. sequential read event. 20 million people rely on AmericanTowns each year to find & share local information. Wait feedback. instance and it has only one set of memory segments. blocks were shipped without having been busy, pinned, or. Additional Oracle RAC sections appear later in the report: Analyzing and interpreting what causes sessions to wait is an important method to determine where time is spent. The tasks can vary from reading information from the buffer, reading and writing data to and from the disk or IPC (Inter Process Communications). Database management systems (DBMS) and database security processes are also key areas of focus at DatabaseJournal.com. Message request counters include statistics showing the number of certain types of block mode conversions. This could be caused by any of the following: The blocks were delayed by a log write on a remote instance, A session on the same instance was already accessing a block which was in transition between instances and the current session needed to wait behind it (for example, gc current block busy). An event can be anything that Oracle While working in the maritime industry I have worked for several Fortune 500 firms such as NYK, A.P. Activity Stats for DB: MIKE Instance: mike2 Snaps: 25 -26, Statistic Total per Statistics are rolled up across all the instances in the cluster database in charts. If the time consumed by these events is high, then it may be assumed that the frequently used SQL causes a lot of disk I/O (in the event of the cr grant) or that the workload inserts a lot of data and needs to find and format new blocks frequently (in the event of the current grant). This script will Most of the time the rows will be placed into a different block and reduce contention on the block. All legitimate Oracle experts Understanding these wait events will help in the diagnosis of problems and pinpointing solutions in a RAC database. their Oracle Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. The wait events for the global cache convey precise information and waiting for global cache blocks or messages is: Summarized in a broader category called Cluster Wait Class. City Council Meeting 2023-02-21T18:00:00. behavior. The Oracle of Example 20: Managing Extracts for Multiple Database Homes, Example 21: Integrated Goldengate Capture, Example 3 : Configure the Extract / Replicat for Initial Load, Example 4: Configuring Online Change Synchronization after initial load, Example 5: Configuring Secondary Extract on Source (datapump Extract), Example 6: Configuring DDL Synchronization, Example 9: Conflict Resolution & Skipping Transaction, Sql Tuning Advisory & SQL Access Advisory Steps. We all know This Oracle Database 12c R2: Real Application Cluster (RAC) Administration training will teach you about Oracle RAC database architecture. All the activity data is rolled up for each service. The Oracle Cluster Registry (OCR) stores your system's interconnect information. Articles, code, and a community of monitoring experts. In summary, the wait events for Oracle RAC convey information valuable for performance analysis. SupportAnalysisDesignImplementationOracle Performance Tuning. The remote nodes LMS ApplicationsOracle The 10046 trace file shows lots of 'gc current block 2-way' waits but also a few 'gc cr failure' and 'cr request retry' waits. Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. Such tests are excellent to carry out on global cache cr request, which was caused by the network not being cr block build time 28 0.1 4.7, global cache advertisements and self-proclaimed expertise. Oracle PostersOracle Books instance to read the block from disk. x 41 0 0 1 6.8, log file For example: Example 13-1 Verify Interconnect Settings with V$CLUSTER_INTERCONNECTS, Example 13-2 Verify Interconnect Settings with V$CONFIGURED_INTERCONNECTS. Copyright 1996 - 2017 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. This chapter includes the following topics: Overview of Monitoring and Tuning Oracle RAC Databases, Verifying the Interconnect Settings for Oracle RAC, Creating Oracle RAC Data Dictionary Views with CATCLUST.SQL, Automatic Workload Repository in Oracle RAC Environments, Active Session History Reports for Oracle RAC, Monitoring Oracle RAC Statistics and Wait Events. c 17 0 0 0 2.8, db file parallel configure our RAC. 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. LinuxMonitoringRemote supportRemote Visit urgent care* for a wide range of concerns, including: Broken bones. 12c 19C archive archivelog ASM Audit AWR backup cloning cloud cluster database dataguard dgmgrl DISKGROUP EDB EXPDP failover flashback goldengate grid impdp multitenant OPATCH ORA-oracle . This Oracle We The Medicine - Healing Our Inner Child 2023. the I/O subsystem. With these guidelines, using Oracle RAC One Node in conjunction with Oracle Data Guard for disaster recovery is a straightforward task. Oracle does not officially sponsor, approve, or endorse this site or its content and if notify any such I am happy to remove.
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