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Re: RAC problem, is gc_files_to_locks is needed?

From: tomi wijanto <>
Date: Fri, 22 Oct 2004 03:05:49 -0700 (PDT)
Message-ID: <>

Hi, thanks for your reply..

I tried to get information about resource master in RAC, but i stuck by the column name on view GV$GCSHVMASTER_INFO. What are the meaning of hv_id? can i map to some object? Also the value of current_master and previous_master are strange, what is 0 or 32767 means?

btw, someone ever use parameter gc_files_to_locks? What is the proper value of number of lock for each datafile?


> hi,tomi wijanto
> from oracle document
> Setting this parameter to any value other than the
> default will disable Cache Fusion processing in
> Oracle9i Real Application Clusters.
> from
> Oracle Real Application Clusters
> by Murali Vallath
> Local
> When the block is read for the first time into an
> and there are no other instances in the cluster that
> have read the same block or are holding the block,
> then the block is locally managed
> Global
> If the block that was originally acquired has been
> modified by the holding instance and, based on a
> request from another instance, has transmitted the
> block over. The block that was originally on one
> node is now present in multiple nodes and therefore
> is considered globally managed
> When an instance reads data blocks for the very
> first time, its existence is local, that is, no
> other instance in the cluster has a copy of the same
> block. The block in this state is called a current
> state block (XI). Therefore, the behavior of this
> block in memory is similar to any single instance
> configuration, with the exception that GCS keeps
> track of the block even in a local mode. Multiple
> transactions within the instance have access to
> these data blocks. Once another instance has
> requested for the same block, then the GCS process
> will update the GRD, taking the state of the data
> block from a local role to a global role.
> Best regards
> msn:
> a dba from alibaba(china)
> ---- from the mail-----
> >Hi All,
> >
> >I has oracle9i database with RAC using 2 nodes.
> >The first time i used them, i activated server load
> >balancing, so user connect to least loaded
> instance.
> >
> >But after i checked 'gcs/ges wait' related to cache
> >fusion, that is very large, i activate only one
> node,
> >and use another node as failover node.
> >What i expected here was, i want to reduce
> >intercluster operations for sql/dml.
> >
> >The problem i still got was, when one table was
> >actively update by many users and i did full table
> >scan on it, it's quite slow. I have compared it
> with
> >non-RAC database, it's about 2-3 times slower.
> >I have activated sql trace, and found many2 of
> 'global
> >cr request' wait on that full table scan.
> >
> >So i feel a little confuse now. I guess when
> providing
> >consistent view of updated blocks, the active node
> >still check for existency of those blocks in
> another
> >instance (that should be failed because the node is
> >pasive), and then read from undo segments. That is
> >probably why non-RAC database got faster.
> >
> >The question is: How could i reduce intercluster
> >operation in full table scan. I have read about
> >gc_files_to_locks parameter, but i'm afraid of
> >inflexibility caused by it (that i need to bounce
> >server to change it).
> >Is there any best practice to use
> gc_files_to_locks?
> >I'm really curious on this parameter and wondering
> if
> >it's worthed to considered..
> >
> >Best regards,
> >tomi

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Received on Fri Oct 22 2004 - 05:01:21 CDT

Original text of this message