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  • 1.  IOPS will be zero when use command 'dd' on AIX client

    Posted 04/25/23 08:30 AM

    Hi experts,
    I used command(dd) to test the performance of an AIX client connecting to a storage device over NFS.During the test, the IOPS and bandwidth are 0. However, replacing the linux client does not cause this problem.



    ------------------------------
    leo yang
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  • 2.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/26/23 09:23 AM

    Leo,
    it would be helpful to share the command with all parameters you are using in this test.
    How are you monitoring IO?
    NFS is a cached file system, so your test, and while you monitored, may have just hit the local cache?



    ------------------------------
    Ralf Schmidt-Dannert
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  • 3.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/26/23 11:08 PM

    Hi,
    The command parameters are as follows,
                                        dd if=/dev/zero of=/mnt/data bs=1M

    I used 'topas' to check the network port bandwidth on AIX client and found that the bandwidth was zero.
    I also thought it might be a local cache issue, but with other storage devices the situation was different.I was wondering if there are any NFS server parameters to control the local caching on the client side?



    ------------------------------
    leo yang
    ------------------------------

    Original Message


  • 4.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/27/23 02:52 AM

    Hi Leo

    Are small IO operations successful? Such as touching a file, or copying a small file?
    It may be a jumbo frame issue if small IO is ok, but large IO is getting blocked.



    ------------------------------
    Chris Wickremasinghe
    IBM
    ------------------------------

    Original Message


  • 5.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/27/23 06:48 AM

    I tried small IO operations that also caused the problem.
    The command parameters are as follows,
                                        dd if=/dev/zero of=/mnt/data bs=8k



    ------------------------------
    leo yang
    ------------------------------

    Original Message


  • 6.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/28/23 12:32 AM

    Hi Leo

    It will be useful to know if touch and cp can write to the NFS share.
    touch /mnt/myfile
    cp /etc/motd /mnt
    ls -l /mnt

    Also try:
    ping <NFS_server>
    ping -s 9000 <NFS_server>



    ------------------------------
    Chris Wickremasinghe
    IBM
    ------------------------------

    Original Message


  • 7.  RE: IOPS will be zero when use command 'dd' on AIX client

    Posted 04/28/23 12:29 PM

    Leo please do no -a | grep tcp_sendspace and no -a | grep tcp_recvspace and no -a | grep tcp_rfc1323 settings
    what is the size of tcp_sendspace and recvspace and if rfc1323 is 1 or 0 

    other NFS setting what are they on your server - before you do test?

    # /usr/sbin/nfso -p -o nfs_socketsize=600000
    # /usr/sbin/nfso -p -o nfs_tcp_socketsize=600000
    /usr/sbin/nfso -p -o nfs_use_reserved_ports=1
    /usr/sbin/nfso -p -o portcheck=1
    /usr/sbin/nfso -p -o sockthresh=60



    ------------------------------
    minesh patel
    ------------------------------

    Original Message


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