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  • 1.  IOwait on VMware Instances

    Posted Jun 16, 2008 11:05 AM

    Hi @all,

    I am running VMware ESX3.02 with lots of debian instances and NetApp NFS storage at a customers side. Now there are some instances experiencing

    up to kind of 80-90% IOwait. There seems to be no clear reason for that. CPU overall looks fine, lightly used actually. Latenciesy measured on storage

    also seem to be quite ok.

    Now my question: Is there a VMware-internal possibility to get a better overview of what the instances CPU is doing or even waiting for ? Some kind of

    per-process CPU utilization including per-process iowait statistics ?

    Thanks in advance ... Frank ...



  • 2.  RE: IOwait on VMware Instances

    Posted Jun 16, 2008 11:35 AM

    Did you try the commands : esxtop and top from the service console ?



  • 3.  RE: IOwait on VMware Instances

    Posted Jun 16, 2008 04:36 PM

    Check the esxtop storage stats DAVG and KAVG first. There's information on those and many other counters on the page.



  • 4.  RE: IOwait on VMware Instances

    Posted Jun 17, 2008 11:26 AM

    Hi,

    now I have results of esxtop and nmon for the client. nmon doesn't show this high IOwait and does not show any bottleneck for me. For interpreting

    esxtop results I am not skilled enough, perhaps anyone could help:

    ID

    GID

    NAME

    NMEM

    %USED

    %SYS

    %OVRLP

    %RUN

    %WAIT

    %BWAIT

    %TWAIT

    %CRUN

    %CSTP

    1

    1

    idle

    4

    272.02

    0.00

    0.00

    0.32

    0.00

    0.00

    0.00

    0.00

    0.00

    2

    2

    system

    6

    0.05

    0.00

    0.00

    0.05

    600.00

    0.00

    600.00

    0.00

    0.00

    6

    6

    console

    1

    2.09

    0.03

    0.03

    2.08

    92.20

    6.53

    98.73

    0.00

    0.00

    7

    7

    helper

    13

    0.00

    0.00

    0.00

    0.00

    1300.00

    0.00

    1300.00

    0.00

    0.00

    8

    8

    drivers

    9

    0.01

    0.00

    0.00

    0.01

    900.00

    0.00

    900.00

    0.00

    0.00

    40

    40

    affected-machine

    5

    3.19

    0.17

    0.11

    3.04

    485.72

    15.74

    500.00

    0.00

    0.00

    Thanks for ya help ...



  • 5.  RE: IOwait on VMware Instances

    Posted Jun 17, 2008 07:10 PM

    Try reading the documentation I mentioned in the previous mail. If you find it unclear in some areas, I'm glad to update it. Obviously the storage section will be of particular interest to you.



  • 6.  RE: IOwait on VMware Instances

    Posted Jun 17, 2008 11:41 AM

    I found this forum post maybe it's usefull..

    VMware recommend that under "normal" operating conditions the CPU Ready value should not be above 5%

    As per page 5 of this doc: