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 . the PCI speeds. You can access the Interconnects page by clicking the Interconnect tab on the Cluster Database home page or clicking the Interconnect Alerts link under Diagnostic Findings on the Oracle RAC database home page. The Cluster Database Performance page provides a quick glimpse of the performance statistics for an Oracle RAC database. Aug 8, 2017 7:18AM edited Aug 8, 2017 7:18AM. Oracle Database records information about active sessions for all active Oracle RAC instances and stores this data in the System Global Area (SGA). This compensation may impact how and where products appear on this site including, for example, the order in which they appear. The effect of accessing blocks in the global cache and maintaining coherency is represented by: The Global Cache Service (GCS) statistics for current and cr blocks, for example, gc current blocks received, gc cr blocks received, and so on. The following wait events indicate that the remotely cached blocks were shipped to the local instance without having been busy, pinned or requiring a log flush and can safely be ignored: sync converts 30 0.1 5.0, global lock affinity. Property of TechnologyAdvice. 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. message 9,262 8,501 421 45 1,543.7, wakeup time Wait events for Oracle RAC include the following categories: The main wait events for block-related waits are: 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 1 block transfer. With these guidelines, using Oracle RAC One Node in conjunction with Oracle Data Guard for disaster recovery is a straightforward task. 1.When Instance leaves or joins cluster. single node server, the block is requested by a process, pinning the buffer and independently investigate their credentials and experience, and not rely on Events that start with "GCS%" and "gc%" are Cache Fusion-related waits. will go into more detail when we benchmark our RAC on VMware by stress testing access to the code depot of working RAC scripts, buy it Wanted! 2022 TechnologyAdvice. In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. 1. DB version -12.2.0.1.0 - 64bit Redo log file size-4GB. The chart shows maximum, average, and minimum load values for available nodes in the cluster for the previous hour. time should be tuned first. Two ASH report sections that are specific to Oracle RAC are Top Cluster Events and Top Remote Instance as described in the next two sections. database, contention, message, load and block wait tuning: Contention wait event tuning in RAC: This of a second, -> ordered by wait time desc, These waits also indicate that the remotely cached In order 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 following headings: Analyzing the Effect of Cache Fusion in Oracle RAC, Analyzing Performance Using GCS and GES Statistics. Oracle ASH report statistics provide details about Oracle Database session activity. Ion 29 0 1 18 4.8, library cache Two node RAC cluster. frequently the root cause of the below wait events. Oracle Database must queue these requests. event, count(*) cnt from ServerOracle ConceptsSoftware SupportRemote This script will Oracle Enterprise Manager also provides current data, called real-time data. Select a discussion category from the picklist. Events that start with "ges%' are related to Global Enqueue Services. 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. convert time 171 0.4 28.5, global cache FAN is default, configured and enabled out of the box with Oracle Real Application Clusters All Oracle clients use the Oracle Notification System (ONS) as the transport for FAN FAN is posted by Global Data Services (GDS) to allow FAN events to span data centers FAN is on by Default For Oracle Database 12c, no changes are needed to configure FAN . second or less, hardly a concern when compared with the 154 second retry 27 27 0 0 4.5, gcs remote 911RAC Once your application performs well in a single instance, the benefits can be extrapolated to the RAC instance. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Oracle ACE; MySQL, SQL Server, Sybase and DB2 expert, Pluralsight Developer Evangelist, author, MCTS, MCDBA, MCCAD, Chief Executive Officer, TUSC; Oracle Certified Master, SQL Server MVP and Head Geek at SolarWinds, Understanding Oracle Free Buffer Wait Events, Oracle Block Change Tracking Buffer Wait Event, https://docs.oracle.com/database/121/REFRN/GUID-DA269AB3-4230-4B37-8F33-D3088F6BC1DD.htm#REFRN00513, Free 14-day trial for Oracle, SQL Server, DB2, Sybase, and databases on VMware, No agent and no load on monitored servers. considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on Events for DB: MIKE Instance: mike2 Snaps: 25 -26, -> cs - centisecond - 100th As a trainer (technical as well as non-technical) I have trained staff both on national and international level. Cluster Tips by Burleson Consulting. New Businesses. removed from this listing. Any increases in the average wait times for the events mentioned in the preceding list could be caused by the following occurrences: High load: CPU shortages, long run queues, scheduling delays, Misconfiguration: using public instead of private interconnect for message and block traffic. gc buffer busy release: A session cannot pin the buffer in the buffer cache because another session on another instance is taking the buffer from this cache into its own cache so it can pin it. The Top Cluster Events report lists events that account for the highest percentage of session activity in the cluster wait class event along with the instance number of the affected instances. 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. 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. and system statistics. This information includes: Global cache efficiency percentagesworkload characteristics, Global cache and Enqueue Service (GES)messaging statistics. client 4,040 0 216 53 673.3, SQL*Net message to Here the requesting node makes a request to the GCS (Global Cache In addition, the interconnect bandwidth, its latency, and the efficiency of the IPC protocol determine the speed with which Cache Fusion processes block transfers. 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. resources per ownership. 600 0 1 2 100.0, control file parallel collect items such as waiting sessions, GES lock information Any help is much appreciated. 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. You can then change the interconnect that you are using by running an OIFCFG command. Advertise with TechnologyAdvice on Database Journal and our other IT-focused platforms. cr block send time 117 0.3 19.5, global cache Therefore, In a RAC environment, the buffer cache is global across all instances in the cluster and hence the processing differs. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. This section describes how to monitor GCS performance by identifying data blocks and objects which are frequently used (hot) by all instances. If the data is not in the local buffer cache the global buffer cache will be reviewed to see if another instance already has it in their buffer cache. free 24 0 0 feedback. Visit our Welcome Center. The Oracle of status 15 15 440 29307 2.5, ges remote Presents all the new information needed to effectively use Oracle Real Application Clusters 12c Oracle It can also be its own background process as well. In Oracle RAC environments, each AWR snapshot captures data from all active instances in the cluster. Oracle PostersOracle Books is the registered trademark of Oracle Corporation. Oracle Source : https://docs.oracle.com/database/121/REFRN/GUID-DA269AB3-4230-4B37-8F33-D3088F6BC1DD.htm#REFRN00513, [] Oracle RAC Wait Events Monitoring an Oracle RAC database often means monitoring this situation and the amount of requests going back and forth over the RAC interconnect. A FlashGrid Cloud Cluster is a virtual database infrastructure appliance for Oracle RAC that can be deployed into your AWS accounts. (ms) /txn, ---------------------------- To get immediate Database Support This section describes Active Session History (ASH) reports for Oracle RAC under the following topics: ASH Report for Oracle RAC: Top Cluster Events, ASH Report for Oracle RAC: Top Remote Instance. 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. 133 0 0 0 22.2, KJC: Wait for msg sends to Activate ADDM analysis using the advisor framework through Advisor Central in Oracle Enterprise Manager, or through the DBMS_ADVISOR and DBMS_ADDM PL/SQL packages. The term wait is used Load wait event tuning in RAC: Load I cannot find much if any information on these two wait events. They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. February 21, 2023, 6:00 PM - 8:00 PM. cr block receive tim 1,158 2.7 193.0, global cache The Per Second view shows the number of transactions compared to the number of logons, and the amount of physical reads compared to the redo size per second. Use the V$SESSION_WAIT view to identify objects and data blocks with contention. If it is in a shared mode then the remote node TrainingOracle Most of the time the rows will be placed into a different block and reduce contention on the block. Keep an eye on specific wait-events for Global Cache Services and Global Enqueue Services, they reflect the cache-fusion behavior and the interconnect usage at the RAC instance level. The main wait events for contention-related waits are: The contention-related 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. 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. message times and cache block transfers. Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. If user response times increase and a high proportion of time waited is for global cache, then you should determine the cause. Cache fusion interconnect, load issues, or SQL execution against a large working set is frequently the root cause of the below wait events.
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