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    VM failed and won't start. Displaying "An emulator required to run this VM failed to start"

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    • R Online
      rustylh @olivierlambert
      last edited by

      @olivierlambert "Failed","Shutting down VM 'AlmaLinux8-Testing' on 'iahost-xcpng-server3'
      Internal error: Object with type VM and id dfcdcce6-b6e1-d865-6f2b-472a35b1fae7/config does not exist in xenopsd","iahost-xcpng-server3","Jun 9, 2025 12:28 PM"

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      • olivierlambertO Online
        olivierlambert Vates 🪐 Co-Founder CEO
        last edited by

        That's why you need to power reset it first.

        Also please check the host dmesg

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        • R Online
          rustylh @olivierlambert
          last edited by

          @olivierlambert Oh, I'm sorry. You mean power restart the host server?

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            rustylh @rustylh
            last edited by

            [12:52 iahost-xcpng-server3 ~]# xe vm-reset-powerstate vm=dfcdcce6-b6e1-d865-6f2b-472a35b1fae7 --force
            This operation cannot be completed because the server is still live.
            host: 6985c3a2-091d-488b-8de6-4bf40985987b (iahost-xcpng-server3)

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            • olivierlambertO Online
              olivierlambert Vates 🪐 Co-Founder CEO
              last edited by

              On the pool master:

              1. Restart the toolstack
              2. Immediately after, run the vm reset powerstate command.
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              • R Online
                rustylh @olivierlambert
                last edited by

                @olivierlambert Ok. I was able to get that VM started on another Host. Now, I need to figure out what is going on with server1. I appreciate all your help! If you have any suggestions please let me know.

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                • olivierlambertO Online
                  olivierlambert Vates 🪐 Co-Founder CEO
                  last edited by

                  My suggestion stands from previous messages, check the dmesg output from the problematic host 🙂

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                  • R Online
                    rustylh @olivierlambert
                    last edited by

                    @olivierlambert It is full of these:
                    43342477.643853] sd 7:0:0:1: rejecting I/O to offline device
                    [43342477.643861] print_req_error: I/O error, dev sdb, sector 0

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                    • olivierlambertO Online
                      olivierlambert Vates 🪐 Co-Founder CEO
                      last edited by

                      That's exactly what I suspected. You have a connectivity issue with your shared storage.

                      The device is considered offline because it cannot do any I/O on sector 0

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                      • R Online
                        rustylh
                        last edited by

                        said in VM failed and won't start. Displaying "An emulator required to run this VM failed to start":

                        rejecting I/O to offline device

                        I was able to reboot the host. Now things seam fine. Does that make sense? I mean have you seen this happen then a reboot of the host takes care of it?

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                        • R Online
                          rustylh @olivierlambert
                          last edited by

                          @olivierlambert I had the same issue this morning on one of the hosts I rebooted and was working fine. An emulator required to run this VM Failed to start. sd 7:0:0:1: rejecting I/O to offline device. I am not sure what to check next.

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                          • R Online
                            rustylh
                            last edited by

                            xcp-ng iscsiadm -m session -P 3 Attached scsi disk sdb State: offline

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                            • olivierlambertO Online
                              olivierlambert Vates 🪐 Co-Founder CEO
                              last edited by

                              There's something fishy about the connectivity to your storage.

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                                rustylh @olivierlambert
                                last edited by

                                @olivierlambert I am looking into that. I just do not have much experience with the networking.

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                                  rustylh
                                  last edited by

                                  I found that the SR has two NICs bonded to two different hardware switches on the iSCSI LUN. Then each host has a management network(Bonded NICS on hosts) and VM network (Bonded NICS). Should I break the SR bond and just go with one NIC? If so, I assume I would be best to shutdown the VMs until I have one NIC on SR reconfigured?

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                                    rustylh
                                    last edited by

                                    Additional finding. The two switches (LAG) are Cisco with STP enabled.

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                                    • R Online
                                      rustylh
                                      last edited by

                                      I am still getting " sd 7:0:0:1: rejecting I/O to offline device" taking all VMs on host down. I then shutdown the VM and power them on, on another Host. I have 4 host in a pool connected iSCSI to a Synology LUN. What is the best way to troubleshoot network issues on xcp-ng.
                                      Thank you

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                                      • R Online
                                        rustylh
                                        last edited by

                                        Just adding another note. When I reboot the host everything is fine then the issues pops back up. There doesn't seem to be any consistency as far as timeframe in between. It just happens randomly

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                                          rustylh
                                          last edited by

                                          Any help is greatly appreciated.

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                                          • olivierlambertO Online
                                            olivierlambert Vates 🪐 Co-Founder CEO
                                            last edited by

                                            That's not a trivial problem that you have, it seems to be intermittent and could be anything between host and the storage. I assume you can see the issue as soon you have the rejecting I/O to offline device right?

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