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Intermitent values of %wio, avwait > avserv

NDO
Super Advisor

Intermitent values of %wio, avwait > avserv

Hi All

 

I have a ia64 hp server BL860c running 11.31 with its storage being a NetApp. I seem to be having disk bottleneck, but I could not yet find out what is causing, here are my findings:

  • using sar -Mu I found high values of %wio compared to %idle  (intermittent: some times %idle is 100)
  • using sar -d I found high %busy, avque and avwait bigger than avserv
  • the busy disks belong to a VG with lots of space,
  • using sar -b I found 100 for %rcache, but very very low %wcache
  • using kcusage -t filemax_cache I found that BC is using about 78% of its max value

All of this in one minute, next 5 min or so, becomes normal again.

Please can you help in finding what is causing it?

 

FR