From: me@some.where.com   
      
   Hi!   
      
   For a few months we suffer mysterious problem with Oracle 10g RAC (more   
   details on server configuration at the bottom). At regular basis (every 5   
   minutes) nodes of our cluster "freeze" - during couple of seconds   
   operating system for some mysterious reason does nothing - as far as we're   
   concerned - in userspace. Every single userspace process stops for this   
   period. After a few seconds system comes back to life and all suspended   
   processes content for CPU time and other resources, which in effect leads   
   to higher load.   
      
   We tried many investigations, which brougt us to following conclusions:   
   - when Oracle instance is stopped, freezes disappear   
   - since the moment we reduced shared_servers parameter from 60 to 20   
   freezes last unsignificantly shorter (about 4 seconds shorter)   
   - after instance restart freezes are unnoticeable, but as times   
   goes by, they are again as long as 6-9 seconds   
      
   Unfortunately investigation is very hard. /var/log/messages reports   
   nothing, dmesg reports nothing, Oracle alert log also has nothing to say.   
      
   Have you any idea what may be misconfigured or damaged? Could you please   
   suggest us some further tests?   
      
      
   Thank you in advance for any followups!   
      
      
      
   Database server characteristics   
   -------------------------------   
   OS: RHEL 3 ES   
   Kernel: 2.4.21-32.ELsmp   
   Oracle: 10.2.0.1.0   
   Storage: SAN accessed by QLogic HBA   
   Cluster storage: OCFS v.1   
      
      
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   -- There are only 10 types of people in this world; --   
   -- those who understand binary, and those who don't --   
      
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