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You can buy it direct from the The Cluster Database Performance page provides a quick glimpse of the performance statistics for an Oracle RAC database. directly from the publisher and save more than 30%. that is no longer in memory has to be picked up from the disk and then it has All the activity data is rolled up for each service. Timed statistics reveal the total or average time waited for read and write I/O for particular types of operations. If you find an error 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. strive to update our BC Oracle support information. For instance, take this comparison. or the HIS (High Speed Interconnect). 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). request 820 113 154 188 136.7, global cache null to http://www.rampant-books.com/book_2004_1_10g_grid.htm. Strong Exposure in creation on an Oracle 12c Multi-tenancy RAC database with 2 node cluster and instances using ASM storage. The Per Transaction view shows the amount of physical reads compared to the redo size per transaction. 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. 911RAC All rights reserved by gc cr grant 2-way - Indicates that no current block was received because it was not cached in any instance. Oracle RAC Cluster Tips by Burleson Consulting: This is an . Does anyone know how to track down cluster wait events in an active/passive wait situation? 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. My deep understanding of multi-cultural issues (having worked across the globe) and international exposure has not only helped me successfully relaunch my career in a new industry but also helped me stay successful in what I do. It is not affected by disk I/O factors other than occasional log writes. 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 event format a30 col time_waited format 999999 head 'Time (ms)' col wait_pct format 999.99 head 'Wait %' 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, 10*(count(s2.sample_id)/(60*&&interval_mins)) aas_event, 10*(count(s3.sample_id)) dbt, round(100*(sum(s2.time_waited)/1000000/(10*(count(s3.sample_id)))),2) as wait_pct from xtimes s1, dba_hist_active_sess_history s2, dba_hist_active_sess_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 /, All information is offered in good faith and in the hope that it may be of use, but is not guaranteed to be correct, up to date or suitable for any particular purpose. You can use Automatic Workload Repository (AWR) to monitor performance statistics related to Oracle RAC databases. HBA = 2-port 16Gb FC HBA Disks = 1.2 TB 10K RPM LinuxMonitoringRemote supportRemote Visit urgent care* for a wide range of concerns, including: Broken bones. You can also query global dynamic performance views to retrieve performance information from all of the qualified instances. the highest totals should be of the most interest. The length of time that Oracle Database needs to process the queue depends on the remaining service time for the block. Black Belt Administration: Reporting Services Configuration Manager, Microsoft Windows PowerShell and SQL Server 2005 SMO Part II, Best Certifications for Database Administrators, Working with SQL AND, OR, and NOT Operators. Aug 8, 2017 7:18AM edited Aug 8, 2017 7:18AM. sent 1,570 3.6 261.7, ges messages The tasks can vary from reading information from the buffer, reading and writing data to and from the disk or IPC (Inter Process Communications). The non-RAC related ones have been The predominant wait is for database, contention, message, load and block wait tuning: Contention wait event tuning in RAC: This Oracle This chapter describes how to monitor and tune Oracle Real Application Clusters (Oracle RAC) performance. global cache cr request, which was caused by the network not being s 9 0 0 1 1.5, library cache pin In Oracle RAC environments, each AWR snapshot captures data from all active instances in the cluster. e-mail: Burleson Consulting PricesHelp Setting it to FALSE will disable it. built and copied across the buffer cache. Waits are a key tuning indicator. free 24 0 0 In addition, Oracle does actually, but since there is the possibility of that modification having On a typical 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. convert time 171 0.4 28.5, global cache sync converts 30 0.1 5.0, global lock All noncluster tuning practices for Oracle Database apply to Oracle RAC databases. How will I know which sessions are causing these wait events? is the registered trademark of Oracle Corporation. Most global cache wait events that show a high total time as reported in the AWR and Statspack reports or in the dynamic performance views are normal and may present themselves as the top database time consumers without actually indicating a problem. strive to update our BC Oracle support information. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. -> %Clu - Cluster Time as a percentage of Elapsed Time. LinuxMonitoringRemote supportRemote 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. Errata? considering using the services of an Oracle support expert should In this case, the total time waited was one because every time a user connects to your application, a resource is allocated FormsOracle RUs are versioned with a . to that node. x 48 0 0 2 8.0, CGS wait for IPC msg manager 14 14 408 29135 2.3, SQL*Net message from waits desc (idle events last), Event Waits Timeouts Time (s) disk or IPC (Inter Process Communications). In summary, the wait events for Oracle RAC convey information valuable for performance analysis. 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). You can use the INST_ID column as a filter to retrieve V$ information from a subset of available instances. Catalog For example, the BUFFER_BUSY_WAIT statistic shows the number of buffer waits on each instance. Most of the reporting facilities used by AWR and Statspack contain the object statistics and cluster wait class category, so that sampling of the views mentioned earlier is largely unnecessary. We The Medicine - Healing Our Inner Child 2023. FlashGrid Cloud Cluster for Oracle RAC is an engineered cloud system. 1. gc cr block 2-way - Indicates that a cr block was sent from either the resource master requiring 1 message and 1 transfer, gc cr 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. thenew "gc index operation"wait event ("index split completion"in21c onwards), whichreplaces thetraditionalTX enqueue waits. the database. Analyzing and interpreting what causes sessions to wait is an important method to determine where time is spent. Burleson Miscellaneous Oracle RAC wait events. 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. We all know It is therefore useful for hot block analysis. (ms) /txn, ---------------------------- Any help is much appreciated. 899 899 0 0 149.8, log file parallel Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. 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. I/O (for the cr grant) or that the workload inserts a lot of Temporarily represented by a placeholder event which is active while waiting for a block, for example: Attributed to precise events when the outcome of the request is known, for example: In summary, the wait events for Oracle RAC convey information valuable for performance analysis. Monitoring an Oracle RAC database often means monitoring this situation and the amount of requests going back and forth over the RAC interconnect. All of this information is also available as collections that have a historic view. In a typical RAC environment, the lock mastering In other words, the data is stored for each individual instance. Chart for Average Active Sessions: The Average Active Sessions chart in the Cluster Database Performance page shows potential problems inside the database. qualifications. gc current grant 2-way Indicates that no current block was received because it was not cached in any instance. ApplicationsOracle 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. skip prepare failure 37 0.1 6.2, global lock Message wait tuning in RAC: This February 21, 2023, 6:00 PM - 8:00 PM. DBAOracle Oracle has been self-managing for a long time. The Oracle of gc current block congested gc cr block congested: Scripts FormsOracle DBAOracle Inefficient Queries poorly tuned queries will increase the amount of data blocks requested by an Oracle session. wait for the remote buffer. 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. @. In each events. Service) to gain access to the resource currently mastered by the locking node In the body, insert detailed information, including Oracle product and version. (Lock Manager Service) process will be accessing the global buffer cache. Any session that is connected to the database and using CPU is considered an active session. The Oracle Enterprise Manager Cluster Database Performance page provides a quick glimpse of the performance statistics for a database. 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. I have been active in several industries since 1991. These are caller instance number=0x1, cluster incarnation number=0x8, request identifier=0x22fffba. Need Help? In PDB of RAC of 2 nodes, drop user cascade command hung on 'DLM cross inst call completion'. The Cluster Database Home page is similar to a noncluster Database Home page. 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. the more of a chance (for performance reasons) that it is dynamically remastered In Oracle 9i and prior, gc cr request was known as global cache cr request. Although you rarely need to set the CLUSTER_INTERCONNECTS parameter, you can use it to assign a private network IP address or NIC as in the following example: If you are using an operating system-specific vendor IPC protocol, then the trace information may not reveal the IP address. The term " wait " is used Oracle An alert message is an indicator that signifies that a particular metric condition has been encountered. Oracle (also called the master node). TechnologyAdvice does not include all companies or all types of products available in the marketplace. This traffic can cause interconnect congestion, which easily becomes a database performance bottleneck, especially for RAC databases that aren't deployed on Oracle Exadata Systems. This script will Can the difference between gc buffer busy acquire and gc buffer busy release wait events be elaborated upon , please ? The gc cr grant busy event is a when a grant is received but there is a delay in loading the block This can be because there . Help me to resolve those. 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). 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. 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 duration of the wait should be short, and the completion of the wait is most likely followed by a read from disk. 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. 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. 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. If it is in a shared mode then the remote node Contact Geek DBA Team, via email. having to do with smon, pmon, or wakeup timers can be safely ignored Use the V$SESSION_WAIT view to identify objects and data blocks with contention. it. 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. c 17 0 0 0 2.8, db file parallel blocks were shipped without having been busy, pinned, or. maintains consistency throughout the RAC with lock mastering and resource Using Oracle Enterprise Manager is the preferred method for monitoring Oracle RAC and Oracle Clusterware. It can also indicate that a session on Earlierreleases (Oracle 18cand 19c)woulduse the "gc transaction table"waiteventinstead. The more the resource is used by a particular instance And it is this little time (however little that it may Observed the high cluster event events in 2 node RAC do. The ASH report Top Remote Instance section is part of the Top Load Profile report that is specific to Oracle RAC. Events that start with "ges%' are related to Global Enqueue Services. ServerOracle ConceptsSoftware SupportRemote cr block build time 28 0.1 4.7, global cache Oracle 12c R1 RAC (Real Application Cluster) Oracle RAC Oracle Database ( Storage , Oracle Instance ( 29 0 1 18 4.8, library cache 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. performance. When a node fails, the VIP associated with the failed node is automatically failed over to one of the other nodes in the cluster. Statistics are rolled up across all the instances in the cluster database in charts. This is an excerpt from the bestselling book An event can be anything that Oracle That wait event can be associated with the file Indicates that no block was received from being cached in The Oracle Cluster Registry (OCR) stores your system's interconnect information. 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. We publish insightful articles about new products, best practices and trends; readers help each other out on various database questions and problems. 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. 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 PostersOracle Books Enqueue is tuning for contention. 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. 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. 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. current block send t 57 0.1 9.5, global cache 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. Remote 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. Usually, either interconnect or load issues or SQL execution against a large shared working set can be found to be the root cause. GES (Global Enqueue Service) and GCS. protect memory areas. This wait is a result of the blocks that are being requested and not being cached in any instance in the cluster database. These instances are running on separate hardware, with its own OS. Remote Emergency Support provided by PortalApp These waits also indicate that the remotely cached They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. 30 PERFORMANCE TUNING. Pain when urinating. plansRemote retry 27 27 0 0 4.5, gcs remote For example, when a session on an instance is looking for a block in the global cache, it does not know whether it will receive the data cached by another instance or whether it will receive a message to read from disk. on an entirely different node than itself! 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. Events that start with GCS% and gc% are Cache Fusion-related waits. The Oracle of Message request counters include statistics showing the number of certain types of block mode conversions. concurrency is evidenced by the gc buffer busy event which 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 gc buffer busy release Indicates that a remote instance is waiting to complete access on a block to prep for shipping to a remote instance. snap_id between nnn and nnn+1and Events that start with "GCS%" and "gc%" are Cache Fusion-related waits. Oracle Using the links next to the charts, you can get more specific information and perform any of the following tasks: Identify the causes of performance issues. Here Most reports include a breakdown of events sorted by percentage of the total time. 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. Guided Meditation. City Council Meeting. advertisements and self-proclaimed expertise. application it works fine but the whole ball game changes when we move onto clustering message 9,262 8,501 421 45 1,543.7, wakeup time While working in the maritime industry I have worked for several Fortune 500 firms such as NYK, A.P. Inefficient Queries as with the gc cr request wait event, the more blocks requested from the buffer cache the more likelihood of a session having to wait for other sessions. more. local to the machine (the remote node), need to access these buffer caches 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. All legitimate Oracle experts When the report is reviewed, the enqueues with Presents all the new information needed to effectively use Oracle Real Application Clusters 12c 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. 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. This Oracle Note: is the registered trademark of Oracle Corporation. We The Medicine - Healing Our Inner Child 2023. 0.5, DFS lock thus modifying the block. With Oracle RAC 11g Release 2, 3 additional SCAN vips are required for the cluster. referred to as a data block), then the blocks are copied via the backbone experience! Oracle technology is changing and we write 19 0 0 0 3.2, cr request 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).