The value of correct sizing in the Cloud
The Cloud is rising and the growth predictions are insane. Often we aren’t even aware when we are making use of the Cloud. Think about Hotmail, Office 365, Citrix Cloud or even websites like Airbnb. Not owning the servers, like Airbnb does with houses, but also with their website back-end, isn’t the only advantage of the Cloud. Other advantages are obvious: scalability, flexibility, disaster recovery, etc. But those advantages come at a cost. With a pay-per-user model like Office 365, the costs are evident. But if you go to an Infrastructure-as-a-Service (IaaS) model it can become confusing. Choosing the right amount of cloud resources is crucial to get the best value for money.
I can’t count the amount of times I have seen the Iceberg image on LinkedIn passing by. This image shows the advantages of cloud computing but also shows the disadvantages. The Cloud takes away much of the work, but the costs remain. Cloud providers will include them within the price of VMs/instances. This means within each VM or instance the costs of the (underwater) iceberg remains hidden and will be included in the subscription fee.
These cloud solutions are expensive with these hidden costs. If you don’t make use of the flexibility, like reducing the amount of VMs at night, the costs can make the Cloud a useless option. The same goes for the correct environment sizing. My colleague Brian showed earlier how easy it is to test desktops on AWS. If you undersize your environment, you will get a poor performance/user experience. But when oversizing, you would receive a high bill.
Let’s look at an example. If we assume the ideal density is like Brian tested: 42 users on a M4.2XLarge AWS instance. With those instances, we want to serve 2000 XenApp users. How much would these instances cost?
So, let’s assume we don’t use the ideal density and use a lower number of users per instance (oversizing) as shown in the table below.
These examples show that user density is key. In this scenario, you could save up to 20K per month, or 240K a year. Therefore, you should test your ideal density before spinning up too many instances—using the right amount will save you a lot of money!