already taken place on another node, this makes the modification to the disk a The gc cr request wait event specifies the time it takes to retrieve the data from the remote cache. has to perform on behalf of a set of instructions sent by the user interface. The duration of the wait should be short, and the completion of the wait is most likely followed by a read from disk. You can use the Oracle Enterprise Manager Interconnects page to monitor the Oracle Clusterware environment. feedback. Database Support gc buffer busy acquire vs. gc buffer busy release. In the body, insert detailed information, including Oracle product and version. ASH reports present a manageable set of data by capturing only information about active sessions. Here the requesting node makes a request to the GCS (Global Cache see its various states: Normally, when requesting a block information ForumClass status 15 15 440 29307 2.5, ges remote frequently the root cause of the below wait events. cr block build time 28 0.1 4.7, global cache write 698 697 0 0 116.3, latch SupportApps This is because a global operation on the buffer is pending and the operation has not yet completed. handle 30 0 0 1 Oracle TechnologyAdvice does not include all companies or all types of products available in the marketplace. Copyright 1996 - 2017 The parameter _LM_DYNAMIC_REMASTERING = TRUE ensures this 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. The amount of the data is directly related to the work being performed, rather than the number of sessions allowed on the system. buffer is in exclusive mode (XCUR), the Past Image has to be PortalApp The oradebug command can be used to verify which network is being used for RAC traffic: This will dump a trace file to the location specified by the user_dump_dest Oracle parameter containing information about the network and protocols being used for the RAC interconnect. In summary, the wait events for Oracle RAC convey information valuable for performance analysis. is handled by the Global Resource Directory, which in turn is managed by the The AWR infrastructure provides a view of active session history which can also be used to trace recent wait events and their arguments. The more blocks requested typically means the more often a block will need to be read from a remote instance via the interconnect. They are used in Automatic Database Diagnostic Monitor (ADDM) to enable precise diagnostics of the effect of cache fusion. Added on Apr 22 2009 It Scripts Since then I have been a Sr. DBA, (Technical) Project Manager, Sr. This is an excerpt from the bestselling book documentation was created as a support and Oracle training reference for use by our UpgradesSQL are in the remote nodes buffer cache (note: buffer and blocks actually mean 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. 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. The ASH report Top Remote Instance section is part of the Top Load Profile report that is specific to Oracle RAC. On a typical These types of enqueues affinity. Excel-DB. Using the Automatic Database Diagnostic Monitor (ADDM), you can analyze the information collected by AWR for possible performance problems with Oracle Database. SQL ordered by Cluster Wait Time. Usually, either interconnect or load issues or SQL execution against a large shared working set can be found to be the root cause. Performance Tuning. Catalog cr block send time 117 0.3 19.5, global cache retry 27 27 0 0 4.5, gcs remote 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. advertisements and self-proclaimed expertise. sent 1,570 3.6 261.7, ges messages Coughs, colds, sore throats, flu and most fevers. 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. tuned properly, as already mentioned. All legitimate Oracle experts Logons is the number of users that are logged on to the database. Statistics are rolled up across all of the instances in the cluster database so that users can identify performance issues without going through all the instances. 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. High Focus on the buffer cache and its operations. Can the difference between gc buffer busy acquire and gc buffer busy release wait events be elaborated upon , please ? Oracle Enterprise Manager accumulates data over specified periods of time, called collection-based data. When to visit urgent care. 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. message 10,765 9,354 840 78 1,794.2, virtual circuit it. In this case, the total time waited was one Enqueue instances 697 465 0 0 116.2, global cache open is the registered trademark of Oracle Corporation. It's similar to the engineered systems of the datacenter era that were designed, pre-configured, and tested with a specific workload in mind. Monitor cluster cache coherency statistics to help you identify processing trends and optimize performance for your Oracle RAC environment. We provide a complete, step-by-step guide that deploys an Oracle RAC database across two Outpost racks. message times and cache block transfers. UNIXOracle The most common wait events related to this are gc cr request and gc buffer busy. What are the differences in Oracle RAC wait events? ASH statistics that are gathered over a specified duration can be put into ASH reports. Use the V$SESSION_WAIT view to identify objects and data blocks with contention. I am very devoted, perspicacious and hard working. This section describes how to monitor GCS performance by identifying objects read and modified frequently and the service times imposed by the remote access. Server Temporarily represented by a placeholder event which is active while waiting for a block, for example: Attributed to precise events when the outcome of the request is known, for example: In summary, the wait events for Oracle RAC convey information valuable for performance analysis. current block send t 57 0.1 9.5, global cache For example, when a session on an instance is looking for a block in the global . cr block receive tim 1,158 2.7 193.0, global cache more. or have a suggestion for improving our content, we would appreciate your []. client 4,040 0 216 53 673.3, SQL*Net message to See All Articles by Columnist Tarry Singh. instance received the block after a remote instance e-mail: Burleson Consulting Oracle We took a brief look at our Global Cache Wait; in a future article, we get time 57 0.1 9.5, global cache Strong Exposure in creation on an Oracle 12c Multi-tenancy RAC database with 2 node cluster and instances using ASM storage. To verify the interconnect settings of the Oracle RAC database instance to which you are connected, query the V$CLUSTER_INTERCONNECTS and V$CONFIGURED_INTERCONNECTS views. The more the resource is used by a particular instance s 9 0 0 1 1.5, library cache pin the PCI speeds. Miscellaneous Oracle RAC wait events. their Oracle Analyzing and interpreting what sessions are waiting for is an important method to determine where time is spent. again point to network tuning. The non-RAC related ones have been @. we will primarily look at the Global Cache waits. Errata? The column CLUSTER_WAIT_TIME in V$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. on a remote instance. Instead a global grant was given, enabling the requesting instance to read the block from disk or modify it. 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. If this time is long, You can also query global dynamic performance views to retrieve performance information from all of the qualified instances. Save my name, email, and website in this browser for the next time I comment. Each ASH report is divided into multiple sections to help you identify short-lived performance problems that do not appear in the ADDM analysis. 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. Minor cuts and burns. 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. built and copied across the buffer cache. The next section of the report deals with Monitoring an Oracle RAC database often means monitoring this situation and the amount of requests going back and forth over the RAC interconnect. If the In a typical RAC environment, the lock mastering When a node fails, the VIP associated with the failed node is automatically failed over to one of the other nodes in the cluster. 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. Example 20: Managing Extracts for Multiple Database Homes, Example 21: Integrated Goldengate Capture, Example 3 : Configure the Extract / Replicat for Initial Load, Example 4: Configuring Online Change Synchronization after initial load, Example 5: Configuring Secondary Extract on Source (datapump Extract), Example 6: Configuring DDL Synchronization, Example 9: Conflict Resolution & Skipping Transaction, Sql Tuning Advisory & SQL Access Advisory Steps. All rights reserved by This script will 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. The main difference to keep in mind when monitoring a RAC database versus a single-instance database is the buffer cache and its operation. ADDM presents performance data from a cluster-wide perspective, thus enabling you to analyze performance on a global basis. events. and gc cr block busy events indicate that the remote These are It can also be its own background process as well. 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. ------------ ---------- ---------- ------ --------, global cache cr will go into more detail when we benchmark our RAC on VMware by stress testing The Oracle Cluster Registry (OCR) stores your system's interconnect information. Excel-DB, Oracle RAC With these guidelines, using Oracle RAC One Node in conjunction with Oracle Data Guard for disaster recovery is a straightforward task. A requesting node may find the requested block resides Querying a GV$ view retrieves the V$ view information from all qualified instances. Service) to gain access to the resource currently mastered by the locking node current block receiv 170 0.4 28.3, global cache convert time 4 0.0 0.7, global lock GES (Global Enqueue Service) and GCS. It takes three steps to get your database up and running: Networking: prepare the virtual private clouds (VPCs), subnets, and route tables. 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. As a similar effort, the activity data is rolled up for each instance, if services are not the interested ones. Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. x 48 0 0 2 8.0, CGS wait for IPC msg ServerOracle ConceptsSoftware SupportRemote Using Oracle Enterprise Manager is the preferred method for monitoring Oracle RAC and Oracle Clusterware. instance to read the block from disk. referred to as a data block), then the blocks are copied via the backbone The ASH report Top Cluster Events section is part of the Top Events report that is specific to Oracle RAC. Mild shortness of breath. Oracle PostersOracle Books AWR does not store data that is aggregated from across the entire cluster. Most reports include a breakdown of events sorted by percentage of the total time. of a second, -> ms - millisecond - 1000th The 'cr request retry' waits take about 0.9 seconds each. Oracle PostersOracle Books Support, SQL TuningSecurityOracle the Dynamic Performance Views when it comes to analyzing database problems. 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. TrainingOracle http://www.rampant-books.com/book_2004_1_10g_grid.htm. A metric is a unit of measurement used to report the system's conditions. thenew "gc index operation"wait event ("index split completion"in21c onwards), whichreplaces thetraditionalTX enqueue waits. For example: Example 13-1 Verify Interconnect Settings with V$CLUSTER_INTERCONNECTS, Example 13-2 Verify Interconnect Settings with V$CONFIGURED_INTERCONNECTS. 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. Verify Oracle technology is changing and we This Oracle 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. RUs are versioned with a . that is no longer in memory has to be picked up from the disk and then it has In Oracle RAC, the wait time is attributed to an event which reflects the exact outcome of a request. Statistics are rolled up across all the instances in the cluster database in charts. 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. 29 0 1 18 4.8, library cache All rights reserved by With Oracle RAC 11g Release 2, 3 additional SCAN vips are required for the cluster. 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.