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Thread: vmware iscsi performance tuning?

  1. #1

    Default vmware iscsi performance tuning?

    I do not see anywhere about vmware esxi 4.1 iscsi performance tuning with open-e. I did see the how to on multi pathing and that worked like a charm. Just wanting to know if there are any other values that can be tweaked?

  2. #2


    We haven't certified with the esxi 4.1 yet but you can test with increasing the Jumbo frames from the Console enter CTRL ALT W then tuning options, make sure to check with your NIC vendor on the recommended size, typical values can be 9000 but could be different from the vendor also you can test with

    I would test with the Block I/O as we certified it with ESX 4.0.

    You can also enable the WB for the LUN but this is only recommended to be used without the replication as we don't replicate the cache.

    Also see the thread on where "icepicknz" made tests with the iSCSI target options from the Console tuning options located at CTRL ALT W then iSCSI daemon options.

    ""I have gone from 200mbps write to around 800mbps""

    MaxRecvDataSegmentLength 262144
    MaxBurstLength 1048576
    MaxXmitDataSegmentLength 262144
    FirstBurstLength 262144
    All the best,

    Todd Maxwell

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  3. #3
    Join Date
    Aug 2010


    And please keep in mind when using latest builds of DSS, MaxBurstLength variable cannot be set to 16776192 because such value was only supported in iSCSI Enterprise Target (IETD), additionally With reads variable also works only with (IETD).

    Max value in SCST for MaxBurstLength is 1MB, 10485760.

    In case when you use MaxBurstLength=16776192 and make the update, scripts during starting the system fix the values to default one (262144).

    So you may leave MaxBurstLength variable values as the default value or you may use the max value which is 10485760.
    Last edited by Al-S; 08-27-2013 at 10:14 AM.

  4. #4
    Join Date
    Oct 2010


    the complete list for best results:

    MaxBurstLength= 1048576

    Be sure to set the same values at the initiator as well.

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