iostat puzzle
Tolga Evren
tolgae at paro.com.tr
Thu Oct 6 05:49:27 UTC 2005
Hi ,
The below is the iostat output redhat linux 3.0 which shows very large
values for rkB/s field (568785.19 )
Reading 568785.19 kB per second! Impossible.
$uname -a:
Linux koccrmdev 2.4.21-15.ELsmp #1 SMP Thu Apr 22 00:18:24 EDT 2004
i686 i686 i386 GNU/Linux
$ cat /etc/redhat-release
Red Hat Enterprise Linux ES release 3 (Taroon Update 2)
I have oracle running on this server. I can basically regenerate this
pattern easily ,this happens when i disable async. io at oracle part .
With aio enabled , oracle does not use pread or readv system calls and
i see reasonable values at iostat for the system.
But when i disable it , iostat shows very high values.
For clarity , when i get these results , the only user on the system is
me.
avg-cpu: %user %nice %sys %idle
20.83 0.00 68.98 10.19
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz avgqu-sz await svctm %util
/dev/sda 127851.85 7748.15 14344.44 879.63 1137570.37 69007.41
568785.19 34503.70 79.25 1966.67 12.91 1.22 1851.85
/dev/sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
/dev/sda2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
/dev/sda3 127824.07 37.04 14118.52 77.78 1135540.74 918.52 567770.37
459.26 80.05 1914.81 13.48 1.30 1851.85
/dev/sda5 27.78 12.96 18.52 9.26 370.37 177.78 185.19 88.89
19.73 2.96 10.67 8.00 22.22
/dev/sda6 0.00 7698.15 207.41 792.59 1659.26 67911.11 829.63
33955.56 69.57 48.70 4.89 4.00 400.00
Can this be a redhat bug?
Kind Regards,
tolga
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