sar -u cpu %idle

[joephilip]

We are experiencing performance problem with our E4000 box with A5200 array. sar -u shows that cpu %idle is below 20%. I ran a script to caputre the top information while the cpu %idle from sar -u goes below 20%. This is what it shows. I can see a 34.5% I/O wait on the system. Does it mean that the system processes are I/O bound processes? What is the measurement so that I can definitely say that the system problem are due to slow I/O.


Mar 02 14:42: CPU %Idle Below 20
******************************************************************************
DATE TIME usr% sys% wio% idle%
Mar 02 14:42 41 21 25 14
load averages: 4.66, 5.98, 5.50 14:43:07
248 processes: 244 sleeping, 1 running, 1 stopped, 2 on cpu
CPU states: 24.2% idle, 23.8% user, 17.5% kernel, 34.5% iowait, 0.0% swap
Memory: 4.0G real, 66.0M free, 3.7G swap in use, 1.3G swap free

 

[rgc41]

I will suggest to check
sar -dq
and check if realy the I/O are bound or if the q size is too higth.

If you are runing an Oracle application, I will suggest to check the oracle parameters, or the SGA used if it is too small.