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    Xen Orchestra Load Balancer - turning on hosts

    Scheduled Pinned Locked Moved Xen Orchestra
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    • B Offline
      berish.lohith @olivierlambert
      last edited by

      @olivierlambert I see what you did there 😄

      1. My mistake - currently I use SMB shared storage, not NFS.

      smb1.PNG
      smb2.PNG

      1. Booted up the pool, waited for LB to shut down everything except master. Then decided to snapshot the XOA itself using XCP-ng center.
        smb3.PNG

      No issues whatsoever. Just disks, with memory, everything is fine. The XOA is on SMB SR.

      1. Snapshoted the XOA using... XOA.
        smb4.PNG

      Also no issues. 🤷

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

        🤔 I would have asked to live migrate on the left host, but IDK how many hosts you have in your pool. Also, please don't provide XCP-ng Center screenshot, I'm allergic to this tool, that I will hope will die at some point 😆 (when XO Lite will replace it)

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        • B Offline
          berish.lohith @olivierlambert
          last edited by

          Live migrate VM from one host to another? That was working yesterday, as long as I exclude the host from LB. I can do that if you come up with a test-case 🙂

          You may be allergic to XCP-ng, but sometimes it is the single reason to have windows installed 😄 There are some things that are easier to find (like WoL settings, I found it by mistake in XCP-ng, no idea where it is in Orchestra), but most important thing is that Center is outside the pool, so in case of screw-up I can control the pool and start Orchestra 🙂

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

            As it will be possible with XO Lite 😉

            Anyway, back to the topic, I wonder if the behavior is different between NFS and SMB shared SR 🤔 I do remember seeing those limitation with "half powered on" pool, but I don't remember which operations exactly.

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            • B Offline
              berish.lohith @olivierlambert
              last edited by

              @olivierlambert said in Xen Orchestra Load Balancer - turning on hosts:

              Anyway, back to the topic, I wonder if the behavior is different between NFS and SMB shared SR I do remember seeing those limitation with "half powered on" pool, but I don't remember which operations exactly.

              State right now is that SR is "Broken" because it is Unplugged from hosts... because, you know... the hosts are down.

              Snapshotting works, migration works as well (when hosts in pool are down). Also, IIRC there are no issues when hosts in a pool are down and VMs are hosted on the SR storage. That is something that happened quite often in many previous projects.

              So my issue with LB plugin is deterministic way of knowing under which conditions will it spin hosts back up.

              @olivierlambert said in Xen Orchestra Load Balancer - turning on hosts:

              As it will be possible with XO Lite

              That is awesome, no more Windows for me 🙂

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              • B Offline
                berish.lohith @berish.lohith
                last edited by berish.lohith

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                • B Offline
                  berish.lohith @olivierlambert
                  last edited by

                  @olivierlambert

                  By looking into the source of the plugin, it looks like all the currently implemented behavior is observed.

                  It calculates/simulates the best plan, moves VMs and tries to shut down the host. Nothing about waking the hosts up.

                  And that makes sense, as the feature of spinning hosts back up should be implemented elsewhere (in context of density plan) - when starting VM, instead of providing the error message "No hosts that are able to run this VM are online", there should/could/may be:

                  1. Evaluation of which host is the smallest one which would be able to host the desired VM (partially implemented in density-plan) and WoL/iDrac/iLO packet send to it(implemented in performance plan)
                  2. Some timeout/waiting for boot pop-up/dialog/having this thing in queue
                  3. After set time (let's say 5 min), call the currently implemented logic of starting VM in a pool.

                  P.S. Would be nice to be able to set, how often the plan is evaluated (currently 1 minute), so until "spinning hosts back up" functionality is implemented, at least host started manually won't be shut down by plan immediately.

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

                    Adding @ronan-a in the loop so we don't forget this

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                    • B Offline
                      berish.lohith @olivierlambert
                      last edited by

                      @olivierlambert Thank you!

                      ronan-aR 1 Reply Last reply Reply Quote 0
                      • ronan-aR Offline
                        ronan-a Vates 🪐 XCP-ng Team @berish.lohith
                        last edited by

                        @berish-lohith Just FYI I created a card in our backlog, I don't see too many blocking points to implement it correctly. 😉

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