How to execute QueryChangedDiskAreas using MOB

If you are not used to working with the vSphere Managed Object Browser (MOB) it can be a little bit tricky to execute the QueryChangedDiskAreas.

Here is a step-by-step guide:


MOB content

  • search for “root folder / ManagedObjectReference:Folder” and select “ha-folder-root”

MOB ha-folder-root

  • search for “childEntity” in the properties area and select “ha-datacenter”

MOB ha-datacenter

  • now select the datastore where the virtual machine resides. You should find a list of the datastores in the properties area, search for Name: datastore | type: ManagedObjectReference:Datastore

MOB datastore

  • in the last line of the properties area you can find the value: vm – select the appropriate VM:

MOB vm

  • now write down or copy the value “rootSnapshot | ManagedObjectReference:VirtualMachineSnapshot” – it should be something similar like “27-snapshot-68”:

MOB snapshot ID

  • scroll down in the same window to the Methods area and look out for “QueryChangedDiskAreas”  – click on the link:

MOB QueryChangedDiskAreas

  • a new window will open – it is named “DiskChangeInfo QueryChangedDiskAreas”

Type in the following values:

Parameter: snapshot -> replace MOID with the value copied before (eg. 27-snapshot-68)
Parameter: deviceKey -> to query the first vmdk file, enter: 2000
to query the second vmdk file, enter: 2001
Parameter: startOffset -> enter: 0
Parameter: changeID -> enter: *

MOB DiskchangeInfo

  • to start the query,  click on the link “Invoke Method”. You can print the output eg. using a pdf converter or copy it to a text-/wordfile.

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