RE: High "global cache blocks lost" statistics on one RAC node
- From: "Powell, Mark D" <mark.powell@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 7 Sep 2005 17:58:05 -0400
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@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Hameed, Amir
Sent: Wednesday, September 07, 2005 4:38 PM
To: racdba@xxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
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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