RE: High "global cache blocks lost" statistics on one RAC node

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Wed, 7 Sep 2005 17:58:05 -0400
Message-ID: <5A14AF34CFF8AD44A44891F7C9FF41050395BA95@usahm236.amer.corp.eds.com>

According to the Oracle Documentation you could have a hardware problem.
>>

Undesirable Global Cache Statistics
The following are undesirable statistics, or statistics for which the values should always be zero or near-zero.

global cache blocks lost --This statistic reveals any block losses during transfers and high values may indicate network problems. When using an unreliable IPC protocol such as UDP, the value for 'global cache blocks lost' may be non-zero. If this is the case, then the ratio of 'global cache blocks lost' divided by 'global cache current blocks served' plus 'global cache cr blocks served' should be as small as possible. A non-zero value for 'global cache blocks lost' does not necessarily indicate a problem, because Oracle retries the block transfer operation until it is successful. Unlike TCP/IP, UDP/IP is considered unreliable because UDP/IP provides very few error recovery services.

global cache blocks corrupt --This statistic indicates whether any blocks were corrupted during transfers. High values for this statistic indicate an IPC, network, or hardware problem. <<

Oracle9i Real Application Clusters Deployment and Performance Ch 4, Monitoring Real Application Clusters Performance

Interesting how the great majority seem to have been lost on one side of what appears to be a two-instance RAC environment.

HTH -- Mark D Powell --

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Hameed, Amir Sent: Wednesday, September 07, 2005 4:38 PM To: racdba_at_freelists.org; oracle-l_at_freelists.org Subject: High "global cache blocks lost" statistics on one RAC node

I have a two-node RAC running an 11i-ebusiness suite (11.5.9/9.2.0.6 64-bit). I am seeing the following from Statspack:

Inst    Statistic                                             Total

per Second per Trans

-----   ---------------------------------------- ------------------
-------------- ------------ 
1.      global cache blocks lost                                 28
0.0          0.0 
2.      global cache blocks lost                              4,410
2.7          0.9

We are using three giga-bit private interconnects going through a switch. This does not see like an interconnect issue otherwise, I think, I would have seen a higher number on the 1 node as well.

Any idea what might be causing it?

Thanks
Amir

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Received on Wed Sep 07 2005 - 17:01:02 CDT