2 Replies Latest reply on Aug 20, 2014 7:59 AM by JPM300

    VCAP-DCD Study Resources

    crawfordm Expert
    vExpert

      I am looking for some study resources that will help me practice calculating compute resources (cpu, mem & nic) for for a design scenario.  

       

      I had some questions on the exam that I don't think I answered correctly because I did not calculate resource correctly.

       

      Thanks

      Marc

        • 1. Re: VCAP-DCD Study Resources
          beeguar Enthusiast
          vExpert

          My experience on the exam was similar. Additional material on the topic would be appreciated.

          • 2. Re: VCAP-DCD Study Resources
            JPM300 Expert

            Hey guys,


            I haven't attempted the DCD yet and I know you can't really give out examples but is this the kind of things you are looking for:

             

            Example:

             

            Company X Transport wants to run 400 VMs with 15% growth expected each year for the next 3 years

             

            Workload Assesment

            400 VMS

            426GHZ CPU Capacity, 615GB Memory Capacity

             

            Each of the current VM's will generate an average of 60 IOPS at 65/35 read/write split and will require 38GB of storage capacity.  Average network utilization for each worload is averaging around 60Mbps

             

            Question:  Using a server with 16 cores(Dual 8 Core CPU) at 2.2GHZ/core and 96GB of RAM, how many servers are required to meet the capacity and growth expecations?

            So 2.2GHZ per core with 16 cores per host, each host has a total of: 35.2 GHZ

            35.2GHZ / 426 GHZ = 12.1 round to 13 Hosts to meet current CPU capacity of 400 VM's

            Growth is 15% per year which is 60 New VM's per year(400*.15).  Total VM count after 3 years growth 400 + 180 = 580VMS this means the total CPU Capcity in 3 years will be 191.7 + 426 = 617.7.  This is under the assuming each VM average CPU consumptionis still only using 1.055GHZ(426/400)

            35.2GHZ / 617 = 17.52 hosts round to 18 to meet current CPU capacity + Growth, however this is at 100%

             

            Assuming we want each host to run at 80% lets recalculate:

             

            35.2GHZ * .80 = 28.16GHZ per host will be 80%

            80% utalization = 617GHZ / 28.16 = 21.91 hosts rount to 22.

             

            Now with 22 hosts for this client our memory utlization is easy as 22 * 96GB = 2112GB

            since we only need 615GB Memory Capacity at 100% we easily obsorb this, but lets calculate running hosts at 80% usage for memory as well.  96 * .80 = 76.8

            76.8 GB per host * 22 hosts = 1689.6GB

             

            So seeing this we are blowing over the memory requirements by 1TB essentially so in this design we could probably scale back the memory per host to something much smaller like 64GB of memory per host which would still leave 80% usage and have room for expansion.

             

            Is stuff like this what you where reffering to or am I waaay off beat?

             

             

            I also appologise if any math is wrong, I did this really quick.