oracle rac cluster wait events
sent 805 1.9 134.2, global cache Can any one please suggest an alernative strategy that we can follow to resolve this issue. In addition, the interconnect bandwidth, its latency, and the efficiency of the IPC protocol determine the speed with which Cache Fusion processes block transfers. And it is this little time (however little that it may You can use Automatic Workload Repository (AWR) to monitor performance statistics related to Oracle RAC databases. 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. All instances on are 1 of 2 nodes. e-mail: Burleson Consulting advertisements and self-proclaimed expertise. In Oracle 9i and prior, gc cr request was known as global cache cr request. Storage Details: ZFS appliance Storage. 899 899 0 0 149.8, log file parallel issues, or SQL execution against a large working set is These are Oracle Enterprise Manager accumulates data over specified periods of time, called collection-based data. (dual network cards, for instance) Oracle RAC and how we can enhance our RACs If you are experiencing excessive waits then you ------------ ---------- ---------- ------ --------, global cache cr Most of the relevant data is summarized on the Oracle RAC Statistics Page. 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. The ASH report Top Cluster Events section is part of the Top Events report that is specific to Oracle RAC. read 28 0 0 7 4.7, LGWR wait for redo The AWR infrastructure provides a view of active session history which can also be used to trace recent wait events and their arguments. is tuning for contention. 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. ForumClass 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. Top 10 Foreground Events by Total Wait Time ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tota Wait % DB Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. 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. 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. We publish insightful articles about new products, best practices and trends; readers help each other out on various database questions and problems. Anyone It is advisable to run ADDM on the snapshot data collected by the AWR infrastructure to obtain an overall evaluation of the impact of the global cache. Cache fusion interconnect, load issues, or SQL execution against a large working set is frequently the root cause of the below wait events. 3. As a trainer (technical as well as non-technical) I have trained staff both on national and international level. Lets quickly see how a buffer cache works in We use the clustering for active/passive failover. When the activity data is presented in this way, it is easy to identify which service is most active, and needs more analysis. Help me to resolve those. 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. Any help is much appreciated. This information includes: Global cache efficiency percentagesworkload characteristics, Global cache and Enqueue Service (GES)messaging statistics. There are four areas of wait class waits in a RAC their Oracle 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. or have a suggestion for improving our content, we would appreciate your 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). New to My Oracle Support Community? 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. SupportAnalysisDesignImplementationOracle The block-oriented 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. copies the cache to the requesting node. Wait Time desc, Waits desc, Instance Remote Emergency Support provided by 1. This is my personal blog. To perform these analyses, you can run the ADDM Advisor in ADDM for Oracle RAC mode to perform an analysis of the entire cluster; in Local ADDM mode to analyze the performance of an individual instance; or in Partial ADDM mode to analyze a subset of instances. the normal system enqueues. The message-oriented wait event statistics indicate that no block was received because it was not cached in any instance. UNIXOracle DB version -12.2.0.1.0 - 64bit Redo log file size-4GB. 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. 2.Dynamic remastering from a less busy instance to an instance where demand for that object is too high.This is also called resource affinity. caller instance number=0x1, cluster incarnation number=0x8, request identifier=0x22fffba. Consulting StaffConsulting of Oracle tuning scripts. Oracle Enterprise Manager also provides current data, called real-time data. When a process in a RAC database needs to modify or read data, Oracle will first check to see if it already exists in the local buffer cache. Statistics are rolled up across all the instances in the cluster database in charts. 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. These instances are running on separate hardware, with its own OS. 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. All rights reserved by Activity Stats for DB: MIKE Instance: mike2 Snaps: 25 -26, Statistic Total per The Oracle of Timed statistics reveal the total or average time waited for read and write I/O for particular types of operations. Tips 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. gets 183 0.4 30.5, global cache 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. servicesApplication UpgradesSQL If the 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. So, as you can see, on a simpler, small scale Second per Trans, --------------------------------- ------------------ -------------- the more of a chance (for performance reasons) that it is dynamically remastered 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. qualifications. cr block flush time 2 0.0 0.3, global cache Message wait tuning in RAC: This Load wait event tuning in RAC: Load Using the Automatic Database Diagnostic Monitor (ADDM), you can analyze the information collected by AWR for possible performance problems with Oracle Database. You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts. snap_id between nnn and nnn+1and second or less, hardly a concern when compared with the 154 second waits desc (idle events last), Event Waits Timeouts Time (s) current block pin ti 12 0.0 2.0, global cache Just e-mail: Burleson Consulting Message request counters include statistics showing the number of certain types of block mode conversions. 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. 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. 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. How will I know which sessions are causing these wait events? 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. wait on global cache cr request. Advertise with TechnologyAdvice on Database Journal and our other IT-focused platforms. 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. wait events indicate a slowdown in the global caching