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vDS config location and HA

By Hugo Strydom, Managing Consultant, Professional Services

Have you ever wondered what those .dvsData folder is on some of your datastores ? Well in this article I will give some insight to them and what they are used for.

Firstly some information around a vDS switch. Each vDS switch has a UUID in the format : “6a de 0e 50 80 32 76 68-e0 72 fd 00 c3 23 52 92” (as an example). When you look inside a datastore you will sometimes (Will explain just now on when) a .dvsData folder. If you look in there you will see 1 or more of these numbers. Each number correspond to a vDS switch that is used by the ESXi host.

So some rules around these files :

  • The .dvsData folder is only created if you have a VM on that datastore that is attached to a vDS. Thus if there is only VM’s that is attached to a vSwitch on a datastore there will not be a .dvsData folder. Also only the datastore that holds the .vmx config file will have the .dvsData folder.
  • Inside the .dvsData folder there is a UUID number for each vDS switch.
  • Inside the UUID folder is a smaller file that is a number. This number corresponds to the ethernetx.dvs.portId inside the .vmx file of a VM. Below we can see that ethernet0.dvs.portId=10.

     


     

    ethernet0.dvs.switchId = “6a de 0e 50 80 32 76 68-e0 72 fd 00 c3 23 52 92”

    ethernet0.dvs.portId = “10”

    ethernet0.dvs.portgroupId = “dvportgroup-208”

    ethernet0.dvs.connectionId = “177280995”

Now why is this file (“10”) important ? It is needed by HA to restart the VM on another host. Certain information (Port state, MTU, run time packets stats) must be transferred to the new host when starting up the VM and this file has that information. In a vMotion of a VM this information is transferred as part of the copy to the other host.

There is some config files that also important:

  • /etc/vmware/ dvsdata.db
    • Updated by hostd every 5 min
    • Contains data for persistent vdPorts (vmkernel)
  • The smaller files (“10” in our case)
    • Updated with vdPort information every 5 min by hostd
    • Contains data for the VM’s vNIC’s that is attached to the vDS

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