Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Interpreting global cache waits

Interpreting global cache waits

From: Finkelstein, Alec <AFinkelstein_at_lifelinesys.com>
Date: Thu, 28 Oct 2004 09:51:48 -0400
Message-ID: <68A6331009FE4D428649E96192C1DAA306EBFF@corpwinexcl1.lifelinesys.com>


Hello,

We have 2-node OPS cluster (8.1.7.4), mostly OLTP. The system is
(predictably) susceptible to high CPU saturations. From the 10046
traces I see PCM lock contention for indexes of hot (high updates/inserts tables):

global cache lock null to x
buffer busy due to global cache
global cache lock open x

I'm planning to tackle this by doing hash partitioning and splitting the sequence ranges on the nodes. But my question is as follows: how do I prove that the "problem" is the system being starved of CPU / DLM resources (ie not storage)? That is to say, are the waits indication of storage waits, slow cluster interconnect, or saturated CPUs? E.g. when DLM is waiting to convert consistent read PCM lock to exclusive
("global cache lock null to x"), presumably it's waiting for the other
instance to release the block. But what is taking the time - high CPU=20 queues or the fact that the other instance is waiting on something else?

Thanks!

Alec.

--
http://www.freelists.org/webpage/oracle-l
Received on Thu Oct 28 2004 - 08:47:20 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US