2 Replies Latest reply on May 19, 2019 1:47 PM by JDMils_Interactive

    Calculate required resources to down-grade a cluster

    JDMils_Interactive Novice

      I have a cluster which has 14 hosts and averaging around 10% CPU usage and 80% memory usage. I want to reduce the number of hosts by say half so that I can better use the CPU resources of the remaining hosts, and upgrade the memory in them to take on the current memory requirements. Is there an online calculator/formula on how to calculate how many hosts I need minimum to accommodate the current workload? It should be able to tell me how much memory to add to each of the remaining hosts to keep the current workload afloat.

       

      The hosts are UCS B200s which currently have 256GB RAM but can handle up to 1.5TB RAM.

        • 1. Re: Calculate required resources to down-grade a cluster
          daphnissov Guru
          vExpertCommunity Warriors

          It may be something vROps can do, but that's a fairly specific capacity planning requirement. You could also just do the math in your head, which would be fairly easy assuming a pure allocation model. Even though that may be somewhat conservative, you won't have to worry about resource exhaustion. Then add 10% for good measure.

           

          The numbers for memory calc are one thing, but you also need to factor in vCPU-to-pCPU subscription ratios when you compact those workloads. Don't know what those CPUs are or how many physical cores, nor do I know what types of workloads they're running and how tolerant they are of contention, but you may find yourself in a position where you actually need more hosts not from a memory density standpoint but for more physical cores.

          • 2. Re: Calculate required resources to down-grade a cluster
            JDMils_Interactive Novice

            Thanks for the reply and I will note the good points made.