12 Replies Latest reply on Aug 9, 2020 9:04 AM by Lisa Keeler

    VM's sharing same serial number issue

    Ryan Nicosia
      Share This:

      Anybody else run into this and know of a work around?  Here is the scenario:


      server1.domain is deployed on vCenter East with IP


      server2.domain is deployed on vCenter West with IP


      Discovery has full access to scan the OS and is also scanning both vCenters.


      When Discovery scans a Host record is created with no issues.  Serial Number = 12345


      When Discovery scans the scan skips with Skipped (Optimizing on initial scan).


      After digging into the information, it is noted that the "Discovered Virtual Machine" for server1.domain and server2.domain have the same exact Instance ID which is in turn the same exact serial number.


      After talking with our vMWare folks, the following was noted as being true:  VM's can exist in different vCenters with the same Instance ID.  The unique identifier that should be used in Instance UUID as.


      I believe Discovery is inferring that server2.domain is the same as server1.domain because the UUID is the same on both.


      Just trying to figure out if anybody else has run into this and come up with a fix or work around. 

        • 1. Re: VM's sharing same serial number issue
          Lisa Keeler

          You are correct about *why* it occurs.  If the serial number, uuid, etc are matching, then Discovery assumes that the two instances are the same Host.

          Differing IP addresses are not sufficient to decide that the Host is different.


          What else is different?  mac addresses?


          Use this query to see what is different that could contribute to uniqueness ... change the 'abc' to your own host name.

          Or, for two host names, you can do this:     where name in ["host1", "host2"]


          Search FLAGS(include_destroyed) Host where name matches 'abc'

          show name, key, uuid, serial, partition_id, zone_uuid, hostid, zonename, os_type, type, hostname, __all_mac_addrs, virtual,

          destroyed(#) as 'Destroyed?', friendlyTime(destructionTime(#)) as 'DestructionTime', last_update_success, age_count, friendlyTime(creationTime(#)) as 'CreationTime'


          • 2. Re: VM's sharing same serial number issue
            Ryan Nicosia

            This search won't work as Disco is not creating the 2 hosts.


            As noted in my original post though, the unique identifier is Instance UUID.  That is what should be used.

            • 3. Re: VM's sharing same serial number issue
              Lisa Keeler

              Yes, I see my answer didn't make sense ..


              So, UUID is unique.  But, serial# is the same.  And, I guess the host name and uuid keep flip-flopping as each VM is discovered.


              Since UUID is different, and serial number is the same ... if nothing else was the same, then you would get 2 Hosts.

              This topic gets into the nitty gritty of our identity algorithm.


              Tell me about these attributes.  Do they match, or are they different:






              If any of those things are matching in addition to serial#, then I think you will get a new Host.


              Use the query above once in the current state.

              Then, scan the other IP address so that the attributes flip-flop.  Then, run the query again.

              Compare the attribute lists.

              Or, you can "Show History" for the host to see which attributes change between scans.


              You should open a case, IMO, for deeper analysis / and discussion about the problem... so we can see why it occurs and determine if we can do something to correct the problem.

              • 4. Re: VM's sharing same serial number issue
                Ryan Nicosia

                UUID is NOT unique.  Instance UUID is.   Serial # appears to be built from UUID of the discovered virtual machine and that is what vmWare has said can be identical.  But Instance UUID which is different than UUID, is in fact unique regardless of the vCenter a VM is deployed in.


                UUID = same

                Instance UUID = different

                Serial # = same

                IP Address = different

                hostname = different


                Can't see hostid, zone_uuid, or poartition_id and compare because Discovery is not creating 2 hosts.  The data above is what I can see when looking at the Discovered Virtual Machine node.

                • 5. Re: VM's sharing same serial number issue
                  Bob Anderson

                  So, what happened is someone 'cloned/copied' the vm WITHOUT changing the UUID.


                  In this case, the two VMs APPEAR to be the same machine because they ARE the same machine.


                  To resolve this, you need to change the UUID on one of the machines.


                  In the future, whenever vm's are 'cloned/copied'....make sure the 'cloning' process changes the UUID of the 'new' vm OR the UUID is manually changed before starting the 'new' vm.


                  The process to do this (alter the UUID) is different, depending on the virtualization technology used.

                  • 6. Re: VM's sharing same serial number issue
                    Ryan Nicosia

                    Bob, I don't disagree the machine was most likely cloned but it doesn't make it the same machine.  They both live on the network under their own name and own IP and have their own set of software installed on them.  From a inventory and security standpoint, they are absolutely their own entities.  So, I have to be able to account for that.


                    The question, as originally posted was whether or not anybody else has run into this and if they've figured out a way around it.

                    • 7. Re: VM's sharing same serial number issue
                      Stefan Hall


                      I think everyone knows the problem when VMs are cloned. We have adapted the clone process and change the UUID on the fly.

                      • 8. Re: VM's sharing same serial number issue
                        Ryan Nicosia

                        Thanks Stefan.  It sounds like that will have to be our fix.  The good news is this only seems to be impacting a couple dozen VM's at our site so should not be a big problem to have the teams address.


                        Thanks for the feedback.

                        • 9. Re: VM's sharing same serial number issue
                          Stefan Hall

                          I find your information interesting. If BMC adapts the detection of new VMs to the VMware idea, we could do without our adaptation. Wouldn't be bad either.

                          • 10. Re: VM's sharing same serial number issue
                            Lisa Keeler

                            So, "Instance UUID" is unique.  Discovery doesn't even discover that, correct?


                            In order for Discovery to allow your situation:

                            First, Discovery would have to discover "Instance UUID", and second, Discovery would have to utilize "Instance UUID" as an important attribute when deciding on Host Identity for a virtual host.


                            1 of 1 people found this helpful
                            • 12. Re: VM's sharing same serial number issue
                              Lisa Keeler

                              What kind of node are you showing in your screenshot?

                              I searched for instance_uuid attribute in the patterns, and it is set by TKU patterns on a SoftwareInstance.

                              And, I see instance_uuid in the Taxonomy as an attribute of a DiscoveredVirtualMachine node.