2 Replies Latest reply on May 1, 2014 8:03 AM by andyr

    Cloud Cost EC2 Algorithm


      Hi All.  I work in the UK public sector.  UK government has a 'Digital by Default' policy that mandates that cloud infrastructure is used by default, unless there is a very good reason why not to use it in a particular circumstance.


      I was therefore very interested to see the Cloud Cost (EC2) dashboard in Virtualization Manager, which we have recently purchased.  I was surprised to see how expensive the EC2 comparison worked out so have been trying to untangle how it does it.  I have found the algorithms used in the relevant Trend configurations and have put my own data manually into the Amazon pricing guide at http://calculator.s3.amazonaws.com/index.html .  In my case, Solarwinds gave me a monthly cost of $126000.  The nearest I could get with  Amazon was $114000 butthis was using on demand pricing at 100% usage.  You would never do this - on demand is for transient use.  A more realistic one year medium use rate gives a monthly cost of $76000, which is a lot less than Solarwinds predicts - not even in the same ball park.


      Does anyone have any further information about the assumptions made by Solarwinds and why they were picked?  Being able to show cost effectiveness is a big issue for us at the moment. The calculator would be a great weapon in our armoury but I need to know that the figures are defensible.  Any help appreciated.


      I've attached a word doc with the cloud monthly cost algorithm and some screenshots from Amazon showing on demand and 1 year costs.


      Many thanks



        • Re: Cloud Cost EC2 Algorithm

          Hi Andy,

          the costs of using EC2 depend on multiple factors which are unique for each monitored environment, prices change with time and location of the servers etc. Covering that many possibilities is probably beyond the scope of the dashboard, so it is rather a template which you can adapt to your specific needs (the default values could perhaps use a revision though). While I don't know much about the assumptions on which the calculations are based, I can show you how to modify the widget according to your needs.


          The original query (when formatted a bit):

          if  (/virtualMachine/memory <= 1740.8   and /virtualMachine/cpuCount <=1)    then 87.6 else if

              (/virtualMachine/memory <= 1740.8   and /virtualMachine/cpuCount <=5)    then 211.7 else if

              (/virtualMachine/memory <= 7680      and /virtualMachine/cpuCount <=4)    then 350.4 else if

              (/virtualMachine/memory <= 17510.4 and /virtualMachine/cpuCount <=6.5) then 452.6 else if

              (/virtualMachine/memory <= 15360    and /virtualMachine/cpuCount <=8)    then 700.8 else if

              (/virtualMachine/memory <= 7168      and /virtualMachine/cpuCount <=20)  then 846.8 else if

              (/virtualMachine/memory <= 35020.8 and /virtualMachine/cpuCount <=13)  then 1051.2 else 2102.4


          Let's look at the first line of the XPath query you find in the trend's Criteria tab:

          if (/virtualMachine/memory <= 1740.8 and /virtualMachine/cpuCount <=1)  then 87.6 else if

          This line represents Windows on m1.small instance - 1.8 GiB of memory and 1 vCPU. The last number is the price per month. According to your region and billing option, this number should be 31.48. To find the other numbers, select one instance of each kind you would use and change the query according to the output of the calculator like in this screenshot:


          For example, the part of the XPath query corresponding to the line labeled "double me xl" in your screenshot would be the following:

          if (/virtualMachine/memory <= 30720 and /virtualMachine/cpuCount <=8)  then 736.4

          30GiB of memory and 8 vCPUs for $736.4 a month.


          Let me know if this helps.




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