Re: Global Cache and Enqueue Services statistics

From: Tim Gorman <tim_at_evdbt.com>
Date: Mon, 30 Jul 2012 20:39:25 +0000
Message-ID: <W7964582299231343680765_at_webmail6>

Amir,
In a head-to-head comparison of the same workload on similar servers, non-RAC will outperform RAC due to the additional waits introduced by GC and GES, because each I/O and enqueue operation now has to perform additional GC and GES services to maintain cache- and enqueue-coherency across the cluster. In short, waits on Global Cache and Global Enqueue events are exactly what was purchased with RAC.

Perhaps validate the new hardware and storage by re-running the same load test from just one of the three instances started with CLUSTER_DATABASEúLSE?

Hope this helps...

Thanks!

Tim Gorman
consultant => Evergreen Database Technologies, Inc. postal => PO Box 352151, Westminster CO 80035 email => Tim_at_EvDBT.com
mobile => +1-303-885-4526
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Lost Data? => http://www.ora600.be/ for info about DUDE...
-----Original Message-----

From: Hameed, Amir [mailto:Amir.Hameed_at_xerox.com] Sent: Monday, July 30, 2012 02:15 PM
To: oracle-l_at_freelists.org
Subject: Global Cache and Enqueue Services statistics

Folks,I have a three-node Oracle RAC environment running on Solaris 10. TheGrid and DB versions are 11.2.0.3 and 11.1.0.7 respectively. We ran aload test against the environment to simulate our load in production.The transaction timings were off when compared to timings from thesingle instance of the same environment. When I look at AWR from allinstances, the following workload statistics seem a bit high: Avg message sent queue timeAvg global cache current block receive time (ms)Avg global cache cr block flush time The CPU utilization was over 90% idle on each RAC node during the test.The interconnect is an aggregated link of two 10GbE NIC. Database filesare on RAID-5 SSDs where as redo logs are on dedicated RAID-10 SASdrives. Is there anything that I should look at closely that could helpidentify reason for higher timings for these statistics? Also, what isconsidered as good timing for these statistics? Thank you,Amir Instance #1=========Global Cache and Enqueue Services - W

 orkload Characteristics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg global enqueue get time (ms): 1.4 Avg global cache cr block receive time (ms): 3.7 Avg global cache current block receive time (ms): 13.0 Avg global cache cr block build time (ms): 0.0 Avg global cache cr block send time (ms): 0.0 Global cache log flushes for cr blocks served %: 8.0 Avg global cache cr block flush time (ms): 7.5 Avg global cache current block pin time (ms): 6.2 Avg global cache current block send time (ms): 0.3Global cache log flushes for current blocks served %: 13.4 Avg global cache current block flush time (ms): 5.1 Global Cache and Enqueue Services - Messaging Statistics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg message sent queue time (ms): 7736.8 Instance #2=========Global Cache and Enqueue Services - Workload Characteristics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg global enqueue get time (ms): 0.8 Avg global cache cr block 
 receive time (ms): 2.2 Avg global cache current block receive time (ms): 11.2 Avg global cache cr block build time (ms): 0.0 Avg global cache cr block send time (ms): 0.0 Global cache log flushes for cr blocks served %: 6.8 Avg global cache cr block flush time (ms): 12.0 Avg global cache current block pin time (ms): 10.5 Avg global cache current block send time (ms): 0.3Global cache log flushes for current blocks served %: 15.0 Avg global cache current block flush time (ms): 6.4 Global Cache and Enqueue Services - Messaging Statistics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg message sent queue time (ms): 9120.8 Instance #3=========Global Cache and Enqueue Services - Workload Characteristics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg global enqueue get time (ms): 0.6 Avg global cache cr block receive time (ms): 2.9 Avg global cache current block receive time (ms): 10.4 Avg global cache cr block build time (ms): 0.0 Avg global cache cr b
 lock send time (ms): 0.0 Global cache log flushes for cr blocks served %: 7.1 Avg global cache cr block flush time (ms): 9.6 Avg global cache current block pin time (ms): 14.3 Avg global cache current block send time (ms): 0.3Global cache log flushes for current blocks served %: 14.5 Avg global cache current block flush time (ms): 6.5 Global Cache and Enqueue Services - Messaging Statistics~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg message sent queue time (ms): 8390.3 --http://www.freelists.org/webpage/oracle-l

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http://www.freelists.org/webpage/oracle-l Received on Mon Jul 30 2012 - 15:39:25 CDT