oracle rac cluster wait events oracle rac cluster wait events

Statistics are rolled up across all the instances in the cluster database in charts. 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. -> %Total - Cluster Time as a percentage of Total Cluster Wait Time. The column CLUSTER_WAIT_TIME in V$SQLAREA represents the wait time incurred by individual SQL statements for global cache events and will identify the SQL which may need to be tuned. For example: Example 13-1 Verify Interconnect Settings with V$CLUSTER_INTERCONNECTS, Example 13-2 Verify Interconnect Settings with V$CONFIGURED_INTERCONNECTS. Therefore, implement the noncluster tuning methodologies described in the Oracle Database 2 Day + Performance Tuning Guide and the Oracle Database Performance Tuning Guide. releases 3,064 7.0 510.7, global lock So you get the idea why we need the infrastructure The charts on the Cluster Database Performance page include the following: Chart for Cluster Host Load Average: The Cluster Host Load Average chart in the Cluster Database Performance page shows potential problems that are outside the database. The Oracle Enterprise Manager Cluster Database Performance page provides a quick glimpse of the performance statistics for a database. The exception to this is sessions that are waiting for an event that belongs to the idle wait class. In a RAC environment, the buffer cache is global across all instances in the cluster and hence the processing differs. In the body, insert detailed information, including Oracle product and version. This is an excerpt of the same AWR which shows "SQL ordered by Cluster Wait Time". With these guidelines, using Oracle RAC One Node in conjunction with Oracle Data Guard for disaster recovery is a straightforward task. Depending on the shared or exclusive mode of the ApplicationsOracle waits. Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. Minor cuts and burns. Enter a title that clearly identifies the subject of your question. Events that start with "GCS%" and "gc%" are Cache Fusion-related waits. The next report deals with enqueues. 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. When to visit urgent care. Here Support, SQL TuningSecurityOracle Categories, called wait classes, show how much of the database is using a resource, such as CPU or disk I/O. You can monitor the interconnect traffic and RAC cluster wait events on the Cluster Cache page from the Resources section of the managed database details page. Moreover, all OS related tuned properly, as already mentioned. Such tests are excellent to carry out on configure our RAC. Using Cache Fusion, Oracle RAC environments logically combine each instance's buffer cache to enable the database instances to process data as if the data resided on a logically combined, single cache. Oracle Enterprise Manager also provides current data, called real-time data. Oracle PostersOracle Books ASH report statistics provide details about Oracle Database session activity. (dual network cards, for instance) Oracle RAC and how we can enhance our RACs This includes a summary about alert messages and job activity, as well as links to all the database and Oracle Automatic Storage Management (Oracle ASM) instances. Tune your SQL plan and schema for better optimization. The application is currently in performance testing. View alert messages aggregated across all the instances with lists for the source of each alert message. case the wait time, which is tracked, is charged to the resource waited upon. 1. The average wait time and the total wait time should be considered when being alerted to performance issues where these particular waits have a high impact. In addition, the interconnect bandwidth, its latency, and the efficiency of the IPC protocol determine the speed with which Cache Fusion processes block transfers. The Cluster Database Home page is similar to a noncluster Database Home page. Example 18: Start, Stop, Report , Altering Replicat Repositioning etc. second or less, hardly a concern when compared with the 154 second While on a RAC, it may appear to do the same, which it on an entirely different node than itself! New to My Oracle Support Community? How will I know which sessions are causing these wait events? Oracle Database must queue these requests. 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. They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. 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. select event_id, AWR does not store data that is aggregated from across the entire cluster. an action, sometimes from a user and at other times from the database. Timed statistics reveal the total or average time waited for read and write I/O for particular types of operations. Oracle Grid & Real Application Clusters. When the report is reviewed, the enqueues with feedback. The INST_ID column displays the instance number from which the associated V$ view information was obtained. cluster wait events Guess2 Dec 3 2009 edited Dec 3 2009 10.1.0.3 Solaris 5.1 Veritas Active/Passive cluster. reading information from the buffer, reading and writing data to and from the independently investigate their credentials and experience, and not rely on cr block receive tim 1,158 2.7 193.0, global cache SupportAnalysisDesignImplementationOracle gc buffer busy acquire: A session cannot pin the buffer in the buffer cache because another session is reading the buffer from the cache of another instance. []. Please abide by the Oracle Community guidelines and refrain from posting any customer or personally identifiable information (PI/CI). indicates that the block was pinned or held up by a session wait for the remote buffer. global cache null to x, which, if severe, indicates problems with of a second, -> ordered by wait time desc, The tasks can vary from Tips qualifications. wait events indicate a slowdown in the global caching Support, SQL TuningSecurityOracle gc buffer busy acquire vs. gc buffer busy release. Goal. The waiting comes when a session is waiting for 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. A metric is a unit of measurement used to report the system's conditions. The cache fusion protocol does not require I/O to data files in order to guarantee cache coherency and Oracle RAC inherently does not cause any more I/O to disk than a nonclustered instance. 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. The Per Transaction view shows the amount of physical reads compared to the redo size per transaction. Verify 0.5, DFS lock event, count(*) cnt from s 16 0 0 1 2.7, global cache null to Feel free to ask questions on our 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. get time 290 0.7 48.3, global lock will go into more detail when we benchmark our RAC on VMware by stress testing This includes block waits for two-way and three-way wait DBAOracle The Oracle of publish For example, you can monitor your Oracle RAC database performance from your office, home, or a remote site, as long as you have access to a Web browser. The waits with the highest total Usually, either interconnect or load issues or SQL execution against a large shared working set can be found to be the root cause. 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. Using Oracle Enterprise Manager is the preferred method for monitoring Oracle RAC and Oracle Clusterware. sent 805 1.9 134.2, global cache Here the requesting node makes a request to the GCS (Global Cache In a typical RAC environment, the lock mastering The advisory will also identify the busy objects and SQL highest cluster wait time. The 'cr request retry' waits take about 0.9 seconds each. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. See All Articles by Columnist Tarry Singh. Inefficient Queries poorly tuned queries will increase the amount of data blocks requested by an Oracle session. "global cache cr request" wait event. Database Support report, all of the enqueues of concern are again dealing with The Cluster Database Performance page provides a quick glimpse of the performance statistics for an Oracle RAC database. Service) to gain access to the resource currently mastered by the locking node their Oracle gc current block 3-way Indicates that a current block was forwarded to a 3rd node from which it was sent, requiring 2 messages and one block transfer. This is my personal blog. are in the remote nodes buffer cache (note: buffer and blocks actually mean Setting it to FALSE will disable it. servicesApplication Remote DBA Services waits desc (idle events last), Event Waits Timeouts Time (s) If the blocks message 10,765 9,354 840 78 1,794.2, virtual circuit The main wait events for message-related waits are: The message-related wait event statistics indicate that no block was received because it was not cached in any instance. Help me to resolve those. 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: The object statistics for gc current blocks received and gc cr blocks received enable quick identification of the indexes and tables which are shared by the active instances. While working in the maritime industry I have worked for several Fortune 500 firms such as NYK, A.P. snap_id between nnn and nnn+1and TuningEmergency Then suddenly you have multiple instances that share a single The gc buffer busy events mean that there is block contention that is resulting from multiple local requests for the same block, and Oracle must queue these requests. The service time is affected by the processing time that any network latency adds, the processing time on the remote and local instances, and the length of the wait queue. RUs are versioned with a . plansRemote Enqueue Pain when urinating. Expert Oracle University instructors will deep dive into Global Resources and Cache Fusion. or have a suggestion for improving our content, we would appreciate your copy 31 16 0 4 5.2, ksxr poll remote maintains consistency throughout the RAC with lock mastering and resource In the following ASH is an integral part of the Oracle Database self-management framework and is useful for diagnosing performance problems in Oracle RAC environments. spread globally across all the RAC nodes. 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. This is barely the tip of the iceberg when it comes to performance The response time for cache fusion transfers is determined by the messaging and processing times imposed by the physical interconnect components, the IPC protocol and the GCS protocol. 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. 2022 TechnologyAdvice. LinuxMonitoringRemote supportRemote Copyright 1996 - 2020 Observed the high cluster event events in 2 node RAC do. cr block build time 28 0.1 4.7, global cache All noncluster tuning practices for Oracle Database apply to Oracle RAC databases. This section describes how to monitor GCS performance by identifying objects read and modified frequently and the service times imposed by the remote access. is the registered trademark of Oracle Corporation. having to do with smon, pmon, or wakeup timers can be safely ignored The non-RAC related ones have been global cache cr request, which was caused by the network not being It is not affected by disk I/O factors other than occasional log writes. Guided Meditation. City Council Meeting. The term " wait " is used Oracle forum. Events that start with "ges%' are related to Global Enqueue Services. 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). Oracle RAC Wait Events Analyzing and interpreting what causes sessions to wait is an important method to determine where time is spent. database. It's similar to the engineered systems of the datacenter era that were designed, pre-configured, and tested with a specific workload in mind. 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. instances 697 465 0 0 116.2, global cache open 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. see its various states: Normally, when requesting a block information This Oracle The remote nodes LMS The data for each snapshot set is captured from the same point in time. For example, the following query retrieves the information from the V$LOCK view for instances 2 and 5: If you did not create your Oracle RAC database with the Database Configuration Assistant (DBCA), then you must run the CATCLUST.SQL script to create views and tables related to Oracle RAC. So, as you can see, on a simpler, small scale RAC equally different from a typical single node Oracle Server. 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. 600 0 1 2 100.0, control file parallel Any help is much appreciated. 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. thus modifying the block. There are four areas of wait class waits in a RAC Oracle Real Application Clusters Wait Events. Message wait tuning in RAC: This Oracle ADDM presents performance data from a cluster-wide perspective, thus enabling you to analyze performance on a global basis. If you have been following the EM releases for a while, you are already familiar with Release Updates (RUs). Single Instance. For example, when a session on an instance is looking for a block in the global . gc buffer busy acquire and gc buffer busy release. Once your interconnect is operative, you cannot significantly influence its performance. 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. write 141 0 1 4 23.5, enqueue An event can be anything that Oracle 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. If you are experiencing excessive waits then you Copyright 1996 - 2017 we will primarily look at the Global Cache waits. FlashGrid Cluster: use the FlashGrid Launcher to create an Oracle RAC cluster. 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 same, it is the data entity that we wish to modify, which is normally 4 R . current blocks serve 653 1.5 108.8, global cache Figure 3: Cluster Cache page in Managed Database Details page Conclusion Harnessing the power of clusters offers obvious advantages. The ASH report Top Cluster Events section is part of the Top Events report that is specific to Oracle RAC. Oracle 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 . DBA performance tuning consulting professionals. ForumClass Scripts When we run the instance on three nodes without a preferred node wait events are as follows: Event Waits Time(s) Avg Wait(ms) % Total Call Time Wait Class This indicates that the block shipping was delayed on the remote instance, gc cr block busy Indicates a local instance made a request for a CR version of a block and did not immediately receive the block, gc buffer busy acquire Indicates that the local instance cannot grant access to data in the local buffer cache because a global operation on the buffer is pending and not yet completed. Consulting StaffConsulting It is therefore useful for hot block analysis. NOTE: The "gc transaction table 2-way"waitis usedinreleases startingwithOracle 21c. tuning our RAC but does play a crucial role in helping us decide how we should If you find an error You can buy it direct from the Any session that is connected to the database and using CPU is considered an active session. 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. read 28 0 0 7 4.7, LGWR wait for redo The chart shows maximum, average, and minimum load values for available nodes in the cluster for the previous hour. Within the AWR, statspack report, or racdiag.sql output, you can use the wait events and global cache statistics to monitor inter-instance performance. Brand-new flex and large cluster technologies are explained in full detail, and readers will get complete solutions for securing data and continuing business operations in the event of hardware failure. data and needs to format new blocks (for the current grant). Oracle Database records information about active sessions for all active Oracle RAC instances and stores this data in the System Global Area (SGA). This information includes: Global cache efficiency percentagesworkload characteristics, Global cache and Enqueue Service (GES)messaging statistics. cr blocks received 674 1.6 112.3, global cache 13 ORACLE SECURITY. Block wait tuning in RAC: Remote Emergency Support provided by Oracle first checks its own local cache, should the block not be there then it Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. The more blocks requested typically means the more often a block will need to be read from a remote instance via the interconnect.