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Old 10-27-2010, 08:20 AM   #1
turbo_acura
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IOWAIT & Load avg ?!?


Hello!

Can anyone explain the difference between IOWAIT%/IDLE%/LOAD AVG ??

We have a 3 servers (oracle rac) attached to a SAN. When we added another CPU to our 3rd server, the IOWAIT across the oracle rac dropped a lot. We used to get pretty high IOWAIT % before. So I don't really understand how the extra CPU could do this. I thought the IOWAIT % is high because the server is waiting for the SAN, so I thought the SAN was the bottleneck.

So I don't really understand the difference between the 3 things (iowait, idle and load avg).

Could anyone help me understand this? I've looked around the net, but not found any conclusive answers..

Appreciate the help in advance!
 
Old 10-27-2010, 09:47 AM   #2
syg00
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Got sysstat ? - have a look at the manpages for iostat and sar for the definitions.

Won't help - I can't spell RAC, so I don't know how adding an engine will affect workload (and I/O) scheduling and balancing across the cluster. Certainly appears counter-intuitive from a single system setup.
 
  


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