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    XenServer hyperconverged

    IT Discussion
    xenserver xenserver 7 xen orchestra hyperconvergence hyperconverged
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    • FATeknollogeeF
      FATeknollogee @olivier
      last edited by

      @olivier said in XenServer hyperconverged:

      Nope, it will be a dedicated pricing, per pool, without number of hosts or disk space limitations.

      When will pricing be available?

      1 Reply Last reply Reply Quote 0
      • olivierO
        olivier @DustinB3403
        last edited by olivier

        @dustinb3403 said in XenServer hyperconverged:

        So with XOA Free you can get XOSAN?

        Yes, XOA Free + paid XOSAN will work.

        @fateknollogee said in XenServer hyperconverged:

        When will pricing be available?

        It's a matter of weeks.

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

          @olivier said in XenServer hyperconverged:

          @dustinb3403 said in XenServer hyperconverged:

          So with XOA Free you can get XOSAN?

          Yes, XOA Free + paid XOSAN will work.

          @fateknollogee said in XenServer hyperconverged:

          When will pricing be available?

          It's a matter of weeks.

          So then when will the community edition get XOSAN?

          olivierO 1 Reply Last reply Reply Quote 0
          • R3dPand4R
            R3dPand4 @olivier
            last edited by

            @olivier We're talking about node failure where you're replacing hardware correct?
            "On a 2 node setup, there is an arbiter VM that acts like the witness. If you lose the host with the 2x VMs (one arbiter and one "normal"), you'll go in read only."
            So are Writes suspended until the 2nd node is brought back online and introduced to the XOSAN? Obviously that's going to be a lot longer than a few seconds even if you're talking about scaling outside of a 2 node cluster. Do you mean that Writes are suspended or cached in the event of a failure while Host is shutting down and then Writes resume as normal on the Active node? If this is the case when the new Host is introduced to the cluster the replication resumes, correct?

            olivierO 1 Reply Last reply Reply Quote 0
            • olivierO
              olivier @DustinB3403
              last edited by

              @dustinb3403 said in XenServer hyperconverged:

              @olivier said in XenServer hyperconverged:

              @dustinb3403 said in XenServer hyperconverged:

              So with XOA Free you can get XOSAN?

              Yes.

              @fateknollogee said in XenServer hyperconverged:

              When will pricing be available?

              It's a matter of weeks.

              So then when will the community edition get XOSAN?

              Not like this. We'll open source the gluster driver, to allow people to make their own solution (hyperconverged or not). But it won't be turnkey.

              1 Reply Last reply Reply Quote 0
              • FATeknollogeeF
                FATeknollogee
                last edited by

                Are the hosts shown in your example using HW or software RAID?

                What is preferred, HW or software RAID?

                DustinB3403D olivierO 2 Replies Last reply Reply Quote 0
                • DustinB3403D
                  DustinB3403 @FATeknollogee
                  last edited by

                  @fateknollogee said in XenServer hyperconverged:

                  Are the hosts shown in your example using HW or software RAID?

                  What is preferred, HW or software RAID?

                  Based on the blog post I'm guessing HW raid

                  1 Reply Last reply Reply Quote 0
                  • olivierO
                    olivier @R3dPand4
                    last edited by

                    @r3dpand4 said in XenServer hyperconverged:

                    @olivier We're talking about node failure where you're replacing hardware correct?
                    "On a 2 node setup, there is an arbiter VM that acts like the witness. If you lose the host with the 2x VMs (one arbiter and one "normal"), you'll go in read only."
                    So are Writes suspended until the 2nd node is brought back online and introduced to the XOSAN? Obviously that's going to be a lot longer than a few seconds even if you're talking about scaling outside of a 2 node cluster. Do you mean that Writes are suspended or cached in the event of a failure while Host is shutting down and then Writes resume as normal on the Active node? If this is the case when the new Host is introduced to the cluster the replication resumes, correct?

                    Nope, writes are suspended when a node is down (time for system to know what to do). If there is enough nodes to continue, writes are resumed after being paused few secs. If there isn't enough nodes to continue, it will be then in read only.

                    Let's imagine you have 2x2 (distributed-replicated). You lose one XenServer host in the first mirror. After few secs, writes are back without having any service failed. Then, when you'll replace the faulty node, this fresh node will "keep up" the missing data in the mirror, but your VM won't notice it (healing status).

                    1 Reply Last reply Reply Quote 1
                    • olivierO
                      olivier @FATeknollogee
                      last edited by

                      @fateknollogee said in XenServer hyperconverged:

                      Are the hosts shown in your example using HW or software RAID?

                      What is preferred, HW or software RAID?

                      @dustinb3403 said in XenServer hyperconverged:

                      @fateknollogee said in XenServer hyperconverged:

                      Are the hosts shown in your example using HW or software RAID?

                      What is preferred, HW or software RAID?

                      Based on the blog post I'm guessing HW raid

                      It's not that easy to answer. Phase III will bring multi-disk capability on each host (and even tiering). So it means you could use any number of disks on each hosts to make inception-like scenario (replication on host level + on cluster level). But obviously, hardware raid is perfectly fine too 🙂

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                      • DustinB3403D
                        DustinB3403
                        last edited by

                        During an event where a host goes down, and for that brief time period where writes are paused, are those writes cached and then written once the system determines what to do?

                        Or are those writes lost?

                        olivierO 1 Reply Last reply Reply Quote 0
                        • R3dPand4R
                          R3dPand4
                          last edited by

                          @olivier Thank you for clarifying, I'm assuming this would apply principally at least the same to a 2 node cluster? One goes down, writes are briefly suspended, writes resume on the Active node, failed node is replaced, then rebuild/healing process continues on the New node. How long are you expecting for rebuilds? I'm sure that's a loaded question because it's data dependent.....

                          olivierO 1 Reply Last reply Reply Quote 0
                          • olivierO
                            olivier @DustinB3403
                            last edited by olivier

                            @dustinb3403 No writes are lost, it's handled on your VM level (VM OS wait for "ack" of virtual HDD but it's not answering, so it waits). Basically, cluster said: "writes command won't be answered as long as we figured it out".

                            So it's safe 🙂

                            1 Reply Last reply Reply Quote 1
                            • olivierO
                              olivier @R3dPand4
                              last edited by olivier

                              @r3dpand4 This is a good question. We made the choice to use "sharding", which means making blocks of 512MB for your data to be replicated or spread.

                              So the heal time will be time to fetch all new/missing 512MB blocks of data since node was down. It's pretty fast on the tests I've done.

                              R3dPand4R 1 Reply Last reply Reply Quote 1
                              • R3dPand4R
                                R3dPand4 @olivier
                                last edited by

                                @olivier So essentially just deduplication?

                                olivierO 1 Reply Last reply Reply Quote 0
                                • olivierO
                                  olivier @R3dPand4
                                  last edited by olivier

                                  @r3dpand4 That has nothing to do with deduplication. There is just chunks of files replicated or distributed-replicated (or even disperse for disperse mode).

                                  By the way, nobody talks about this mode, but it's my favorite 😛 Especially for large HDD, it's perfect. Thanks to the ability to lose any of n disk in your cluster. Eg with 6 nodes:

                                  This is disperse 6 with redundancy 2 (like RAID6 if you prefer). Any 2 XenServer hosts can be destroyed, it will continue to work as usual:

                                  And in this case (6 with redundancy of 2), you'll be able to address 4/6th of your total disk space!

                                  1 Reply Last reply Reply Quote 1
                                  • olivierO
                                    olivier
                                    last edited by

                                    Here it is with improved pics of XOSAN, I suppose it's more clear now:

                                    0_1505215577248_8_DISPERSE_6(2).PNG

                                    0_1505215604111_5_DISTRIB-REP 3x2.PNG

                                    What do you think?

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

                                      @olivier That picture helps make it way more clear.

                                      Each server is providing 100GB and either are standalone systems (disperse) or are paired (dist. repl).

                                      olivierO 1 Reply Last reply Reply Quote 0
                                      • olivierO
                                        olivier @DustinB3403
                                        last edited by

                                        @dustinb3403 That's it, indeed 🙂

                                        1. fist picture: you can lose up to 2 hosts (any of them)
                                        2. second picture: you can lose up to 3 hosts (1 by pair)
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                                        • FATeknollogeeF
                                          FATeknollogee
                                          last edited by

                                          What is the difference in performance between the two options?

                                          olivierO 1 Reply Last reply Reply Quote 0
                                          • olivierO
                                            olivier @FATeknollogee
                                            last edited by olivier

                                            @fateknollogee said in XenServer hyperconverged:

                                            What is the difference in performance between the two options?

                                            Disperse requires more compute performance because it's a complex algorithm (based on reed-solomon). So it's slower vs replication, but it's not a big deal if you are using HDDs.

                                            However, if you are using SSDs, disperse will be a bottleneck, so it's better to go on replicate.

                                            Ideal solution? Disperse for large storage space on HDDs, and Replicated on SSDs… at the same time (using tiering, which will be available soon). Chunks that are read often will be promoted to the replicated SSDs storage automatically (until it's almost full). If more accessed chunks appears in the future, some chunks will be demoted to "slower" tier and replaced by the new hot ones.

                                            1 Reply Last reply Reply Quote 1
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