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    How many vCPUs can I have?

    IT Discussion
    hyper-v hyper-v 2016 vcpu virtualization hypervisor
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    • scottalanmillerS
      scottalanmiller @MattSpeller
      last edited by

      @MattSpeller said in How many VCPU’s can I have?:

      TL;DR 20

      You CAN have way more than that.

      1 Reply Last reply Reply Quote 0
      • ObsolesceO
        Obsolesce
        last edited by Obsolesce

        The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

        ObsolesceO scottalanmillerS 2 Replies Last reply Reply Quote 1
        • ObsolesceO
          Obsolesce @Obsolesce
          last edited by

          @Obsolesce said in How many VCPU’s can I have?:

          The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

          That said, Hyper-V will tell you that the percent of total system CPU resources given to a VM will be 100% if you allocate the same number of total threads you have to a VM.

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

            @Obsolesce said in How many VCPU’s can I have?:

            The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

            How did you determine that Hyper-V is involved?

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

              In ESXi 5 the limitation would have been 20 vCPUs.

              1 Reply Last reply Reply Quote 0
              • ObsolesceO
                Obsolesce @scottalanmiller
                last edited by Obsolesce

                @scottalanmiller said in How many VCPU’s can I have?:

                @Obsolesce said in How many VCPU’s can I have?:

                The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                How did you determine that Hyper-V is involved?

                be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                Lots of good stuff there.

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

                  @Obsolesce said in How many VCPU’s can I have?:

                  @scottalanmiller said in How many VCPU’s can I have?:

                  @Obsolesce said in How many VCPU’s can I have?:

                  The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                  How did you determine that Hyper-V is involved?

                  be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                  https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                  Yes, we know Hyper-V's limits, but how did you know that he has Hyper-V in the first place? I've done a text search and until you said it, it was never mentioned in the thread.

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

                    @scottalanmiller said in How many VCPU’s can I have?:

                    @Obsolesce said in How many VCPU’s can I have?:

                    @scottalanmiller said in How many VCPU’s can I have?:

                    @Obsolesce said in How many VCPU’s can I have?:

                    The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                    How did you determine that Hyper-V is involved?

                    be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                    https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                    Yes, we know Hyper-V's limits, but how did you know that he has Hyper-V in the first place? I've done a text search and until you said it, it was never mentioned in the thread.

                    It's like Apple or Arch Linux... if someone is using it, they WILL tell you. That he didn't say he was, tells me he's using Hyper-V.

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

                      @Obsolesce said in How many VCPU’s can I have?:

                      @scottalanmiller said in How many VCPU’s can I have?:

                      @Obsolesce said in How many VCPU’s can I have?:

                      @scottalanmiller said in How many VCPU’s can I have?:

                      @Obsolesce said in How many VCPU’s can I have?:

                      The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                      How did you determine that Hyper-V is involved?

                      be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                      https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                      Yes, we know Hyper-V's limits, but how did you know that he has Hyper-V in the first place? I've done a text search and until you said it, it was never mentioned in the thread.

                      It's like Apple or Arch Linux... if someone is using it, they WILL tell you. That he didn't say he was, tells me he's using Hyper-V.

                      So your hypothesis is that a lack of pertinent information means it is a Microsoft user?

                      ObsolesceO 1 Reply Last reply Reply Quote 0
                      • ObsolesceO
                        Obsolesce @scottalanmiller
                        last edited by

                        @scottalanmiller said in How many VCPU’s can I have?:

                        @Obsolesce said in How many VCPU’s can I have?:

                        @scottalanmiller said in How many VCPU’s can I have?:

                        @Obsolesce said in How many VCPU’s can I have?:

                        @scottalanmiller said in How many VCPU’s can I have?:

                        @Obsolesce said in How many VCPU’s can I have?:

                        The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                        How did you determine that Hyper-V is involved?

                        be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                        https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                        Yes, we know Hyper-V's limits, but how did you know that he has Hyper-V in the first place? I've done a text search and until you said it, it was never mentioned in the thread.

                        It's like Apple or Arch Linux... if someone is using it, they WILL tell you. That he didn't say he was, tells me he's using Hyper-V.

                        So your hypothesis is that a lack of pertinent information means it is a Microsoft user?

                        Am I wrong?

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

                          @Obsolesce said in How many VCPU’s can I have?:

                          @scottalanmiller said in How many VCPU’s can I have?:

                          @Obsolesce said in How many VCPU’s can I have?:

                          @scottalanmiller said in How many VCPU’s can I have?:

                          @Obsolesce said in How many VCPU’s can I have?:

                          @scottalanmiller said in How many VCPU’s can I have?:

                          @Obsolesce said in How many VCPU’s can I have?:

                          The maximum you CAN have is 240 vCPUs per VM, which is a limitation of Hyper-V Server 2016.

                          How did you determine that Hyper-V is involved?

                          be176c35-5bb2-4163-8f09-3f1b622f8540-image.png

                          https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/role/hyper-v-server/processor-performance

                          Yes, we know Hyper-V's limits, but how did you know that he has Hyper-V in the first place? I've done a text search and until you said it, it was never mentioned in the thread.

                          It's like Apple or Arch Linux... if someone is using it, they WILL tell you. That he didn't say he was, tells me he's using Hyper-V.

                          So your hypothesis is that a lack of pertinent information means it is a Microsoft user?

                          Am I wrong?

                          Just making sure that I understood you.

                          Although in these cases, I would say that VMware is just as likely.

                          1 Reply Last reply Reply Quote 0
                          • M
                            marcinozga
                            last edited by

                            My rule of the thumb is start with 1 vCPU if it's Linux vm, 2 vCPUs if it's Windows, unless you enjoy Windows updates or Antivirus scans taking hours to complete....

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

                              @marcinozga said in How many VCPU’s can I have?:

                              My rule of the thumb is start with 1 vCPU if it's Linux vm, 2 vCPUs if it's Windows, unless you enjoy Windows updates or Antivirus scans taking hours to complete....

                              This is how I do it too. Unless it's something that does nothing 99.99999% of the time like a license server on Windows.

                              1 Reply Last reply Reply Quote 0
                              • JoelJ
                                Joel
                                last edited by

                                So our host is HyperV 2016 core.

                                So if this is a 20 thread processor, could I be assigning double the amount of vCPUs?

                                The reason I asked is because we did have high cpu usage on our app01 and sqlserver but after adding one additional vcpu this massively helped so I was thinking, should I just double what I’ve got in there already and I’ll be okay?

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

                                  @Joel said in How many VCPU’s can I have?:

                                  So if this is a 20 thread processor, could I be assigning double the amount of vCPUs?

                                  If you assign less than ~18, you are just throwing performance away. The threads will be idle. So yes, assign more.

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

                                    In a situation like this, I would not assign more than 19 vCPU across the workloads.

                                    JaredBuschJ 1 Reply Last reply Reply Quote 0
                                    • JoelJ
                                      Joel
                                      last edited by

                                      Thanks all for the feedback. Useful to know.

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

                                        @Joel said in How many VCPU’s can I have?:

                                        DC- 1
                                        FS - 2
                                        APP - 3
                                        SQL - 4

                                        Into...

                                        DC - 1
                                        FS - 2
                                        APP - 10
                                        SQL - 6

                                        Is probably how I would do it. That's 19.

                                        But check your SQL licensing, that might cost you a fortune to increase it even a little.

                                        ObsolesceO 1 Reply Last reply Reply Quote 0
                                        • ObsolesceO
                                          Obsolesce @scottalanmiller
                                          last edited by

                                          @scottalanmiller said in How many VCPU’s can I have?:

                                          @Joel said in How many VCPU’s can I have?:

                                          DC- 1
                                          FS - 2
                                          APP - 3
                                          SQL - 4

                                          Into...

                                          DC - 1
                                          FS - 2
                                          APP - 10
                                          SQL - 6

                                          Is probably how I would do it. That's 19.

                                          But check your SQL licensing, that might cost you a fortune to increase it even a little.

                                          Virtual MS SQL is 4, more than that costs more.

                                          Reid CooperR 1 Reply Last reply Reply Quote 0
                                          • Reid CooperR
                                            Reid Cooper @Obsolesce
                                            last edited by

                                            @Obsolesce depends on the license. You can get SQL Server in 2, 4, 6, 8, etc. If licensing by core.

                                            ObsolesceO 1 Reply Last reply Reply Quote 0
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