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How to increase dvS max-ports on a host?

  • 1.  How to increase dvS max-ports on a host?

    Posted Feb 27, 2012 02:40 AM

    Hi,

    I've hit a problem with our vSphere 5 DVS confguration on our internal lab; we've been provisioning (via powershell) linked clones of VMs and suddenly (and seemingly randomly) hit a DVS port provisioning failure with a generic and bland error message along the lines of:

    Wait-Task: The operation for the entity VirtualMachine-vm-5131 failed with the following message:
    "A general system error occurred: vDS host error: see faultCause"

    FaultCause tells me nothing.  We're using ephemeral port binding, as I hit this issue 6 months ago and converted all dvPGs across from static/dynamic to ephemeral to try and resolve the problem and eliminate port group port exhaustion as a root cause.  This worked fine, until now.

    Digging into the issue a little further, this problem seemed to be related to a specifc host.  I compared / contrasted to other hosts in the same cluster and identified a potential cause; the net-dvs output indicates that each host allocates a limited number of ports for each DVS:

    /etc/vmware # net-dvs | grep 'max ports'

            max ports: 256

    and I was using almost all of them on this problem host…

    /etc/vmware # net-dvs | grep '.*port [0-9]*:.*' | wc -l

    253

    So, to my question; how can I increase the number of DVS ports that are allocated to a DVS on a given host?   I see an argument to the net-dvs command which (seemingly) allows you to set the number of ports which could be the fix…

    ~ # net-dvs -h

    Warning: This is an unsupported command. Use at your own risk.

    net-dvs -a [ -P maxPorts] switch_name

    Hmmm … don’t like the look of that warning… before I try this out does anyone have any experience or guidance on how to use the net-dvs command?

    Thanks,

    JD