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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 Offline
      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 Offline
        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 Offline
          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 Offline
            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 Offline
              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 Offline
                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 Offline
                  rustylh
                  last edited by

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

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

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

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                    • R Offline
                      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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                      • R Offline
                        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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                        • R Offline
                          rustylh
                          last edited by

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

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                          • R Offline
                            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 Offline
                              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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                              • R Offline
                                rustylh
                                last edited by

                                Any help is greatly appreciated.

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                                • olivierlambertO Offline
                                  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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                                  • R Offline
                                    rustylh
                                    last edited by

                                    Yes

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

                                      At least we know there's a root cause: the device becomes offline. Could it be a power setting or something on the device itself?

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                                      • R Offline
                                        rustylh
                                        last edited by

                                        Well, it doesn't happen to every host at the same time, it's just random.

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                                        • R Offline
                                          rustylh
                                          last edited by

                                          What log is best to look at for network disconnects?

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

                                            Well dmesg is fine, I would also check the switch logs if you have anything happening on the ports where you host are connected. Since you can find when it's happening with dmesg, I would use that to correlate with anything else happening few minutes before.

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