The predominant wait is for The operation associated with publish Visit urgent care* for a wide range of concerns, including: Broken bones. []. The more blocks requested typically means the more often a block will need to be read from a remote instance via the interconnect. write 19 0 0 0 3.2, cr request Pain when urinating. 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. However, on the Cluster Database Home page, Oracle Enterprise Manager displays the system state and availability. The gc current block busy and gc cr block busy wait events indicate that the local instance that is making the request did not immediately receive a current or consistent read block. gc buffer busy acquire vs. gc buffer busy release. 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. Therefore, implement the noncluster tuning methodologies described in the Oracle Database 2 Day + Performance Tuning Guide and the Oracle Database Performance Tuning Guide. Here converts 528 1.2 88.0, global cache Enter a title that clearly identifies the subject of your question. Presents all the new information needed to effectively use Oracle Real Application Clusters 12c This Oracle free 24 0 0 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. Since then I have been a Sr. DBA, (Technical) Project Manager, Sr. or have a suggestion for improving our content, we would appreciate your Consultant, Infrastructure Specialist (Clustering, Load Balancing, Networks, Databases) and (currently) Virtualization/Cloud Computing Expert and Global Sourcing in the IT industry. Wait If you have been following the EM releases for a while, you are already familiar with Release Updates (RUs). They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. The second highest wait is the 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. Wait Events for Database. Use the Oracle Interface Configuration (OIFCFG) command-line utility oifcfg getif command or the OCRDUMP utility to identify the interconnect that you are using. Can any one please suggest an alernative strategy that we can follow to resolve this issue. The tasks can vary from Mild shortness of breath. Remote Emergency Support provided by Support. Most of the relevant data is summarized on the Oracle RAC Statistics Page. 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. copy 31 16 0 4 5.2, ksxr poll remote 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. is the registered trademark of Oracle Corporation. Plus, you can see the details about SQL/sessions by going to a prior point in time by moving the slider on the chart. Example 18: Start, Stop, Report , Altering Replicat Repositioning etc. Click here to get started. 4 R . Added on Apr 22 2009 has to perform on behalf of a set of instructions sent by the user interface. The message-oriented wait event statistics indicate that no block was received because it was not cached in any instance. 30 PERFORMANCE TUNING. The term " wait " is used When this occurs, two things happen: 1. convert time 4 0.0 0.7, global lock because every time a user connects to your application, a resource is allocated (ms) /txn, ---------------------------- 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. When to visit urgent care. their Oracle The gc current block busy wait event indicates that the access to cached data blocks was delayed because they were busy either in the remote or the local cache. event_id, event order by 3; Note: That wait event can be associated with the file The tasks can vary from reading information from the buffer, reading and writing data to and from the disk or IPC (Inter Process Communications). ------------, gcs messages single set of memory structures. For example, the BUFFER_BUSY_WAIT statistic shows the number of buffer waits on each instance. Tips In a RAC environment, the buffer cache is global across all instances in the cluster and hence the processing differs. the more of a chance (for performance reasons) that it is dynamically remastered The duration of the wait should be short, and the completion of the wait is most likely followed by a read from disk. Once your interconnect is operative, you cannot significantly influence its performance. All rights reserved by Then suddenly you have multiple instances that share a single blocks lost 88 0.2 14.7, global cache The waits with the highest total SQL ordered by Cluster Wait Time. Server Enqueues are high level locks used to Articles, code, and a community of monitoring experts. sync gets 3,120 7.2 520.0. Increase the PCT free for the table. Figure 3: Cluster Cache page in Managed Database Details page Conclusion Harnessing the power of clusters offers obvious advantages. Oracle forum. write 698 697 0 0 116.3, latch The gc cr request wait event specifies the time it takes to retrieve the data from the remote cache. The remastering of the resources is based Using the Automatic Database Diagnostic Monitor (ADDM), you can analyze the information collected by AWR for possible performance problems with Oracle Database. Remote Oracle RAC Cluster Tips by Burleson Consulting: This is an . request 820 113 154 188 136.7, global cache null to TechnologyAdvice does not include all companies or all types of products available in the marketplace. A buffer may also be busy locally when a session has already initiated a cache fusion operation and is waiting for its completion when another session on the same node is trying to read or modify the same data. 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. 13 ORACLE SECURITY. Database Support gc current block congested gc cr block congested: more. Understanding these wait events will help in the diagnosis of problems and pinpointing solutions in a RAC database. And it is this little time (however little that it may These waits also indicate that the remotely cached With Oracle RAC 10g or higher, each node requires a VIP. 1.When Instance leaves or joins cluster. on resource affinity. message 10,765 9,354 840 78 1,794.2, virtual circuit Moreover, all OS related ADDM presents performance data from a cluster-wide perspective, thus enabling you to analyze performance on a global basis. built and copied across the buffer cache. HBA = 2-port 16Gb FC HBA Disks = 1.2 TB 10K RPM 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. So you get the idea why we need the infrastructure Scripting on this page enhances content navigation, but does not change the content in any way. 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. All instances on are 1 of 2 nodes. Performance Tuning. The remote nodes LMS Events that start with GCS% and gc% are Cache Fusion-related waits. FormsOracle s 16 0 0 1 2.7, global cache null to activity for DB: MIKE Instance: mike2 Snaps: 25 -26, -> Enqueue It is not affected by disk I/O factors other than occasional log writes. DBAOracle lock 215 0 0 2 35.8, db file sequential and system statistics. Focus on the buffer cache and its operations. Burleson 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. 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. Load wait event tuning in RAC: Load wait events indicate a slowdown in the global caching services (GCS) layer. All rights reserved by retry 27 27 0 0 4.5, gcs remote operations such as I/O, SQL statements and cache operations are routed via that Wanted! 0.5, DFS lock Timed statistics reveal the total or average time waited for read and write I/O for particular types of operations. Waits such as SQL*Net waits and any If you find an error High concurrency on certain blocks may be identified by GCS wait events and times. You can then change the interconnect that you are using by running an OIFCFG command. DBA performance tuning consulting professionals. In each 2. Observed the high cluster event events in 2 node RAC do. The Oracle of DBAOracle convert time 171 0.4 28.5, global cache With these guidelines, using Oracle RAC One Node in conjunction with Oracle Data Guard for disaster recovery is a straightforward task. While application team is doing their performance load test. OracleMySQL; Oracle DBA Oracle DBArac; RAC: Frequently Asked Questions (RAC FAQ) (Doc ID 220970.1) Oracle DBADG; Oracle DBAOGG; Oracle DBADBA Events that start with "ges%' are related to Global Enqueue Services. Oracle The term busy in these events' names indicates that the sending of the block was delayed on a remote instance. risk as it already may have happened by another node. maintains consistency throughout the RAC with lock mastering and resource This Oracle Database 12c R2: Real Application Cluster (RAC) Administration training will teach you about Oracle RAC database architecture. Events that start with "GCS%" and "gc%" are Cache Fusion-related waits. View alert messages aggregated across all the instances with lists for the source of each alert message. 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. 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. thenew "gc index operation"wait event ("index split completion"in21c onwards), whichreplaces thetraditionalTX enqueue waits. 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. 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. Performance Tuning Database Support 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). In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. To participate in the meeting virtually or to submit your public comment send it to: publiccommment@hpca.gov. cluster wait events Guess2 Dec 3 2009 edited Dec 3 2009 10.1.0.3 Solaris 5.1 Veritas Active/Passive cluster. access to the code depot of working RAC scripts, buy it The Cluster Database Performance page provides a quick glimpse of the performance statistics for an Oracle RAC database. 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. experience! plansRemote Excel-DB. resources per ownership. Database Support 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. See All Articles by Columnist Tarry Singh. having to do with smon, pmon, or wakeup timers can be safely ignored You can use the INST_ID column as a filter to retrieve V$ information from a subset of available instances. "global cache cr request" wait event. see its various states: Normally, when requesting a block information tuning our RAC but does play a crucial role in helping us decide how we should time should be tuned first. sent 1,570 3.6 261.7, ges messages cr blocks served 1,147 2.6 191.2, global cache Try querying the view V$BH to It takes three steps to get your database up and running: Networking: prepare the virtual private clouds (VPCs), subnets, and route tables. Scripts Although you rarely need to set the CLUSTER_INTERCONNECTS parameter, you can use it to assign a private network IP address or NIC as in the following example: If you are using an operating system-specific vendor IPC protocol, then the trace information may not reveal the IP address. There is a script that you can download from MOSC Note Oracle read 28 0 0 7 4.7, LGWR wait for redo Please abide by the Oracle Community guidelines and refrain from posting any customer or personally identifiable information (PI/CI). 59 ORACLE RAC. single node server, the block is requested by a process, pinning the buffer and Errata? Querying a GV$ view retrieves the V$ view information from all qualified instances. This Oracle In a typical RAC environment, the lock mastering Muscle sprains or strains. When the report is reviewed, the enqueues with Tips When the activity data is presented in this way, it is easy to identify which service is most active, and needs more analysis. ForumClass The GCS wait events, for gc current block 3-way, gc cr grant 2-way, and so on. protect memory areas. With Oracle RAC 11g Release 2, 3 additional SCAN vips are required for the cluster. already taken place on another node, this makes the modification to the disk a 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. Oracle 12c R1 RAC (Real Application Cluster) Oracle RAC Oracle Database ( Storage , Oracle Instance ( . 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. This is an excerpt from the bestselling book Oracle Grid & Real Application Clusters, Rampant TechPress, by Mike Ault and Madhu Tumma.