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    Infrastructure Needed for Hypervisor Cluster

    IT Discussion
    cluster virtualization virtual storage appliance ipod home lab shared storage
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    • scottalanmillerS
      scottalanmiller @EddieJennings
      last edited by

      @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

      That's what I'm having a hard time wrapping my head around: Making shared storage available without the IPOD.

      IPOD isn't the natural way to have shared storage. In your mind, as many people do because of marketing, the idea that storage is consolidated and external is just assumed, and that naturally leads you to an IPOD. Stop trying to consolidate and externalize as part of your sharing, and magically you go to hyperconvergence.

      DustinB3403D 1 Reply Last reply Reply Quote 0
      • scottalanmillerS
        scottalanmiller
        last edited by

        Watch this video that covers this...

        Youtube Video

        1 Reply Last reply Reply Quote 0
        • EddieJenningsE
          EddieJennings @scottalanmiller
          last edited by

          @scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

          So, if the purpose is to build an IPOD (to learn how the people messed up at the office) then there is nothing to be done but to build one.

          The goal is specifically to not do that. The short-term goal is to learn to build a cluster without an IPOD. The long-term goal is to learn and understand $concepts to be able make intelligent decisions about when / how / why to use clustering (of hypervisors) in the real world.

          scottalanmillerS 2 Replies Last reply Reply Quote 0
          • scottalanmillerS
            scottalanmiller @EddieJennings
            last edited by

            @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

            The goal is specifically to not do that. The short-term goal is to learn to build a cluster without an IPOD.

            That would be hyperconverged.

            EddieJenningsE 1 Reply Last reply Reply Quote 0
            • scottalanmillerS
              scottalanmiller @EddieJennings
              last edited by

              @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

              The long-term goal is to learn and understand $concepts to be able make intelligent decisions about when / how / why to use clustering (of hypervisors) in the real world.

              Clustering is done when the cost of clustering is low versus the risk of not clustering.

              EddieJenningsE V 2 Replies Last reply Reply Quote 1
              • EddieJenningsE
                EddieJennings @scottalanmiller
                last edited by

                @scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

                @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                The goal is specifically to not do that. The short-term goal is to learn to build a cluster without an IPOD.

                That would be hyperconverged.

                Is this how that would look with a two-node setup?

                • Both node A and B would be running their hypervisors (for my lab, it's going to be Hyper-V or KVM)
                • Both node A and B would have enough power to be able to handle all of the deployed VMs. The thought behind this is when Node A need to be rebooted, you evacuate Node A's VMs to Node B. This line of thought would not address how to handle the sudden loss of Node A, unless Node A and B are somehow constantly in sync.
                • Communication between Node A and B would be done through a switch.
                scottalanmillerS 3 Replies Last reply Reply Quote 0
                • EddieJenningsE
                  EddieJennings @scottalanmiller
                  last edited by

                  @scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

                  @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                  The long-term goal is to learn and understand $concepts to be able make intelligent decisions about when / how / why to use clustering (of hypervisors) in the real world.

                  Clustering is done when the cost of clustering is low versus the risk of not clustering.

                  I agree. I think of a healthcare environment such as a hospital being something where the likely cost of clustering is less than the cost of the risk of not having clustering -- since likely they can't be in a situation where say the EMR app isn't available.

                  Perhaps I'm misunderstanding the real meaning of having a cluster. I see it like RAID. In your RAID 1, you have the one drive that fails, but you're not immediately down, nor are you waiting for something to fail over.

                  scottalanmillerS 2 Replies Last reply Reply Quote 0
                  • scottalanmillerS
                    scottalanmiller @EddieJennings
                    last edited by

                    @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                    Is this how that would look with a two-node setup?

                    Node count only matters in a uni-node vs. multi-node perspective. And even then, not really.

                    You can hyperconverge with one node, two, three, four, ten, one thousand. Doesn't matter.

                    You can IPOD at any size, including one node, two, three, four, ten one thousand.

                    1 Reply Last reply Reply Quote 0
                    • scottalanmillerS
                      scottalanmiller @EddieJennings
                      last edited by

                      @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                      Both node A and B would have enough power to be able to handle all of the deployed VMs. The thought behind this is when Node A need to be rebooted, you evacuate Node A's VMs to Node B. This line of thought would not address how to handle the sudden loss of Node A, unless Node A and B are somehow constantly in sync.

                      This is a fine way to look at it. Just remember that your capacity planning here is based on high availability, not on hyperconvergence. HC doesn't require you to provide that level of capacity, HA does. If you want HC + HA, then this is the right way to capacity plan.

                      EddieJenningsE 1 Reply Last reply Reply Quote 0
                      • scottalanmillerS
                        scottalanmiller @EddieJennings
                        last edited by

                        @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                        Communication between Node A and B would be done through a switch.

                        In a two node setup, that would not make sense. The switch is an unnecessary point of failure, cost, and point of latency. Just connect the two nodes directly together for a faster, more robust, cheaper solution.

                        Even with three nodes, you often direct connect all three. Four and larger, it's impractical to do anything but a switch.

                        EddieJenningsE 1 Reply Last reply Reply Quote 1
                        • scottalanmillerS
                          scottalanmiller @EddieJennings
                          last edited by

                          @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                          I think of a healthcare environment such as a hospital being something where the likely cost of clustering is less than the cost of the risk of not having clustering -- since likely they can't be in a situation where say the EMR app isn't available.

                          Actually a hospital often can be without EMR. Not that it isn't good to cluster there, but the needs of an EMR rarely require HA. EMR isn't like the medical equipment itself, which can't fail or people die. EMR being down just delays a doctor somewhat. Bad, yes, but not life threatening.

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                          • EddieJenningsE
                            EddieJennings @scottalanmiller
                            last edited by

                            @scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

                            @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                            Communication between Node A and B would be done through a switch.

                            In a two node setup, that would not make sense. The switch is an unnecessary point of failure, cost, and point of latency. Just connect the two nodes directly together for a faster, more robust, cheaper solution.

                            Even with three nodes, you often direct connect all three. Four and larger, it's impractical to do anything but a switch.

                            I'm thinking the connections being done through using Ethernet and forgot to consider just using cross-over cables to connect the nodes directly.

                            scottalanmillerS 1 Reply Last reply Reply Quote 0
                            • scottalanmillerS
                              scottalanmiller @EddieJennings
                              last edited by

                              @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                              Perhaps I'm misunderstanding the real meaning of having a cluster. I see it like RAID. In your RAID 1, you have the one drive that fails, but you're not immediately down, nor are you waiting for something to fail over.

                              Yes, but unlike RAID which is ridiculously cheap compared to what it protects against, clustering is very expensive compared to what it protects against.

                              Examples to come...

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                              • scottalanmillerS
                                scottalanmiller @EddieJennings
                                last edited by

                                @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                                I'm thinking the connections being done through using Ethernet and forgot to consider just using cross-over cables to connect the nodes directly.

                                We haven't used crossover cables in decades. They went out with hubs 🙂 Just normal cables.

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                                • scottalanmillerS
                                  scottalanmiller
                                  last edited by

                                  RAID's primary function is to protect against data loss, not availability loss. The latter is generally seen as a by product, not a goal. Data loss, for a normal business, has a massive cost and risk compared to availability. One hour of lost productivity is often trivial to absorb and can often even be made up. Losing one hour of customer information could result in pretty tragic loss of information. And RAID tends to protect against a lot of data loss, and a little uptime. Also, RAID costs starts around $100, and average is probably around $800 to implement. But protects against huge data loss in most cases.

                                  Clustering does not protect against data loss (and can actually contribute to data loss if we aren't careful.) Clustering only (under normal conditions) protects against availability loss, the lesser factor with RAID. So we have to justify clustering based solely off of improved up time, not loss of data. That makes it much harder to justify and tips the scales from "always do it" to "almost never do it." The difference is that dramatic.

                                  And the starting cost of clustering is generally several thousand dollars with the average likely being in the tens of thousands.

                                  Also, RAID requires essentially zero IT skills. You can get it as simply as checking a box when ordering a server. Clustering, however, requires a lot of complex interactions, includes a bit of risk, and normally a huge amount of either cost or expertise or both.

                                  So basically... RAID is a few hundred dollars to protect against some of the worst issues you can face, with zero overhead. Clustering costs tens of thousands to protect against something generally trivial with loads of overhead.

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                                  • EddieJenningsE
                                    EddieJennings @scottalanmiller
                                    last edited by

                                    @scottalanmiller said in Infrastructure Needed for Hypervisor Cluster:

                                    @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                                    Both node A and B would have enough power to be able to handle all of the deployed VMs. The thought behind this is when Node A need to be rebooted, you evacuate Node A's VMs to Node B. This line of thought would not address how to handle the sudden loss of Node A, unless Node A and B are somehow constantly in sync.

                                    This is a fine way to look at it. Just remember that your capacity planning here is based on high availability, not on hyperconvergence. HC doesn't require you to provide that level of capacity, HA does. If you want HC + HA, then this is the right way to capacity plan.

                                    So if HA isn't necessary, you could potentially have nodes with various hardware -- such as in my lab where I've accumulated two different servers with different hardware specs: a Dell R310 and a Dell T420. You would then need software to manage the cluster. I assume this is where applications like oVirt or Failover Cluster Manager come into play. If true, then you'd have a VM running on one of the nodes whose purpose is to run the management application.

                                    scottalanmillerS 1 Reply Last reply Reply Quote 0
                                    • 1
                                      1337
                                      last edited by 1337

                                      Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?

                                      Is it vSAN (or equivalent)?

                                      EddieJenningsE ObsolesceO scottalanmillerS 4 Replies Last reply Reply Quote 0
                                      • EddieJenningsE
                                        EddieJennings @1337
                                        last edited by

                                        @Pete-S said in Infrastructure Needed for Hypervisor Cluster:

                                        Maybe a dumb question

                                        Hey now! Only I get to be t3h n00b in this thread 😛

                                        1 Reply Last reply Reply Quote 1
                                        • ObsolesceO
                                          Obsolesce @1337
                                          last edited by Obsolesce

                                          @Pete-S said in Infrastructure Needed for Hypervisor Cluster:

                                          Maybe a dumb question, but was it is that makes it hyperconverged solution compared to "just a bunch of hypervisors" with local storage that are managed together?

                                          Is it vSAN (or equivalent)?

                                          Hyperconverged just means everything is in the same box: storage, compute, network... Vsan has nothing to do with the name.

                                          scottalanmillerS 1 Reply Last reply Reply Quote 1
                                          • scottalanmillerS
                                            scottalanmiller @EddieJennings
                                            last edited by

                                            @EddieJennings said in Infrastructure Needed for Hypervisor Cluster:

                                            So if HA isn't necessary, you could potentially have nodes with various hardware -- such as in my lab where I've accumulated two different servers with different hardware specs: a Dell R310 and a Dell T420.

                                            Sure. People do that all of the time.

                                            EddieJenningsE 1 Reply Last reply Reply Quote 0
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