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    KVM Virtual Machine Boot Order

    IT Discussion
    virtualization kvm boot order
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    • matteo nunziatiM
      matteo nunziati
      last edited by

      The only actual need I got was a vm expecting a postgres to be up. I delayed such a vm. But yes: complex dependency schemas are a PITA but also out of the smb standard scenario imho.

      1 Reply Last reply Reply Quote 0
      • matteo nunziatiM
        matteo nunziati @black3dynamite
        last edited by

        @black3dynamite said in KVM Virtual Machine Boot Order:

        Uncomment START_DELAY=0 in /etc/sysconfig/libvirt-guests file.

        https://access.redhat.com/discussions/685243
        0_1533138645107_8657357f-89b9-4565-a0ba-c6a64389a585-image.png

        0_1533138783472_51e96b88-60ae-443b-8cbc-2c3ebac10574-image.png

        This will kill parallel startup adding a delay between each vm boot

        dafyreD 1 Reply Last reply Reply Quote 2
        • dafyreD
          dafyre @matteo nunziati
          last edited by

          @matteo-nunziati said in KVM Virtual Machine Boot Order:

          @black3dynamite said in KVM Virtual Machine Boot Order:

          Uncomment START_DELAY=0 in /etc/sysconfig/libvirt-guests file.

          https://access.redhat.com/discussions/685243
          0_1533138645107_8657357f-89b9-4565-a0ba-c6a64389a585-image.png

          0_1533138783472_51e96b88-60ae-443b-8cbc-2c3ebac10574-image.png

          This will kill parallel startup adding a delay between each vm boot

          I think that's the point, though. Some of the VMs are starting before the other VMs that they need to work properly.

          matteo nunziatiM 1 Reply Last reply Reply Quote 1
          • matteo nunziatiM
            matteo nunziati @dafyre
            last edited by

            @dafyre nope starting order is still 'random'

            1 Reply Last reply Reply Quote 0
            • DustinB3403D
              DustinB3403
              last edited by

              I still find it odd that there isn't a start priority or weight setting to apply to each VM so the hypervisor could do this automatically. . .

              1 Reply Last reply Reply Quote 2
              • DustinB3403D
                DustinB3403
                last edited by

                XenServer and XCP-ng both have this option to set for individual VM's under "Start options" under properties of each VM.

                By default everything is "0" aka start immediately if configured for Autostart/HA. But it can be changed easily to 1, 2 3 etc and the VM's will boot in that order.

                matteo nunziatiM 1 Reply Last reply Reply Quote 2
                • ObsolesceO
                  Obsolesce @matteo nunziati
                  last edited by Obsolesce

                  @matteo-nunziati said in KVM Virtual Machine Boot Order:

                  @dustinb3403 said in KVM Virtual Machine Boot Order:

                  @obsolesce that's annoying. . .

                  Edit: still annoying but doesn't Hyper-V have startup priority?

                  No it hasnt until I checked 6 months ago. Only way is build a delay schema by hand and assign delays to VM batch start them in layers

                  Hyper-V had startup priority since 2012... fully configurable... startup action and startup delay.

                  matteo nunziatiM JaredBuschJ 2 Replies Last reply Reply Quote 0
                  • matteo nunziatiM
                    matteo nunziati @Obsolesce
                    last edited by

                    @obsolesce said in KVM Virtual Machine Boot Order:

                    @matteo-nunziati said in KVM Virtual Machine Boot Order:

                    @dustinb3403 said in KVM Virtual Machine Boot Order:

                    @obsolesce that's annoying. . .

                    Edit: still annoying but doesn't Hyper-V have startup priority?

                    No it hasnt until I checked 6 months ago. Only way is build a delay schema by hand and assign delays to VM batch start them in layers

                    Hyper-V had startup priority since 2012... fully configurable... startup action and startup delay.

                    You mean you can use action to wait for another vm to be up and running? If so I ignored it. Delay is mostly a workaround as no one really knows when a dependency will be ready!

                    1 Reply Last reply Reply Quote 1
                    • matteo nunziatiM
                      matteo nunziati @DustinB3403
                      last edited by

                      @dustinb3403 but this will include "wait until vm A is operational/service B is available"?

                      DustinB3403D 1 Reply Last reply Reply Quote 0
                      • DustinB3403D
                        DustinB3403 @matteo nunziati
                        last edited by

                        @matteo-nunziati said in KVM Virtual Machine Boot Order:

                        @dustinb3403 but this will include "wait until vm A is operational/service B is available"?

                        The hypervisor has no way of knowing what the VM does, so no. It just says start this VM first, then that one, and then that one etc.

                        matteo nunziatiM 1 Reply Last reply Reply Quote 0
                        • matteo nunziatiM
                          matteo nunziati @DustinB3403
                          last edited by

                          @dustinb3403 said in KVM Virtual Machine Boot Order:

                          @matteo-nunziati said in KVM Virtual Machine Boot Order:

                          @dustinb3403 but this will include "wait until vm A is operational/service B is available"?

                          The hypervisor has no way of knowing what the VM does, so no. It just says start this VM first, then that one, and then that one etc.

                          At this level hyperv acts like xen. Anyway pre post hooks could be available...

                          matteo nunziatiM 1 Reply Last reply Reply Quote 0
                          • matteo nunziatiM
                            matteo nunziati @matteo nunziati
                            last edited by

                            Now to be fair both mine and @dafyre cases could be solved with longer polling intervals, so they are a sysadmin issue not related to virtualization. Anyway hv agents are used for a lot of things, I don't see why they couldn't act as kubernates with containers. I suppose it is just a lack of demand.

                            1 Reply Last reply Reply Quote 0
                            • JaredBuschJ
                              JaredBusch @Obsolesce
                              last edited by

                              @obsolesce said in KVM Virtual Machine Boot Order:

                              @matteo-nunziati said in KVM Virtual Machine Boot Order:

                              @dustinb3403 said in KVM Virtual Machine Boot Order:

                              @obsolesce that's annoying. . .

                              Edit: still annoying but doesn't Hyper-V have startup priority?

                              No it hasnt until I checked 6 months ago. Only way is build a delay schema by hand and assign delays to VM batch start them in layers

                              Hyper-V had startup priority since 2012... fully configurable... startup action and startup delay.

                              This is inaccurate. There is not a priority.

                              Hyper has only ever had this.
                              0_1533154098692_7bc8e1f1-b436-47db-8e4e-726f1555ebb1-image.png

                              ObsolesceO 1 Reply Last reply Reply Quote 1
                              • ObsolesceO
                                Obsolesce @JaredBusch
                                last edited by

                                @jaredbusch said in KVM Virtual Machine Boot Order:

                                @obsolesce said in KVM Virtual Machine Boot Order:

                                @matteo-nunziati said in KVM Virtual Machine Boot Order:

                                @dustinb3403 said in KVM Virtual Machine Boot Order:

                                @obsolesce that's annoying. . .

                                Edit: still annoying but doesn't Hyper-V have startup priority?

                                No it hasnt until I checked 6 months ago. Only way is build a delay schema by hand and assign delays to VM batch start them in layers

                                Hyper-V had startup priority since 2012... fully configurable... startup action and startup delay.

                                This is inaccurate. There is not a priority.

                                Hyper has only ever had this.
                                0_1533154098692_7bc8e1f1-b436-47db-8e4e-726f1555ebb1-image.png

                                Okay, technically incorrect.... I'll give you that.

                                The point I was trying to make, was you can artificially set priority VM booting by adjusting the "startup delay" for each VM.

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