Sunday, October 9, 2016

solaris - What does it mean if iostat shows 100% busy wait but the CPU is completely idle?

What does it mean if iostat shows 100% busy wait but the CPU is completely idle? My application runs for a while, then goes into this state periodically for about 10-20 seconds.



It is transaction processing C++ app on solaris 10.



IO stat output:
extended device statistics cpu
device r/s w/s kr/s kw/s wait actv svc_t %w %b us sy wt id
c0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 0 0 0 100

sd1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
c1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
c6 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0 100
sd19 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd19.fp2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd19.fp4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0

sd20 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd21 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd23 0.0 0.0 0.0 0.0 0.0 1.0 0.0 0 100
sd24 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd25 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd26 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
sd27 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0



vmstat output:



kthr      memory            page            disk          faults      cpu 
r b w swap free re mf pi po fr de sr s0 s1 s2 s3 in sy cs us sy id
0 0 0 10842364 33093436 30 188 0 0 0 0 65 -0 2 3 -0 1327 843 709 0 1 99
0 0 0 3406728 28181464 71 3601 0 0 0 0 0 0 0 0 0 1372 23009 1584 4 0 96
0 0 0 2702996 28030080 0 740 0 0 0 0 0 0 0 0 0 1414 15002 2065 6 0 93
0 0 0 2699448 28016628 0 3 0 0 0 0 0 0 0 0 0 1747 3012 2193 9 1 90
0 0 0 2691728 28009844 0 1 0 0 0 0 0 0 10 10 0 2315 1300 2877 2 0 97

0 1 0 2679788 27957836 0 5033 0 0 0 0 0 0 1 1 0 1895 1945 2658 10 0 90
0 2 0 2654188 27907196 0 0 0 0 0 0 0 0 1 1 0 3566 3788 5495 2 0 98

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