iostat puzzle
Jeremy Lyon
Jeremy.Lyon at us.ibm.com
Thu Oct 6 14:59:50 UTC 2005
Tolga,
What kind of hardware do you have? Have you done some tests (with dd
perhaps) to see if you are actually getting this type of throughput?
Update 2 for RHEL 3 is pretty old. The latest rev of the kernel is
-37.ELsmp. You may want to consider updating.
Jeremy
redhat-list-bounces at redhat.com wrote on 10/05/2005 11:49:27 PM:
> 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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