December 6, 2013 | Written by: Odilon Magroski Goulart Junior
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One of the biggest barriers that you face when thinking about how to move your workload to the cloud is calculating the size required for each instance. Cloud providers can help you with that, but sometimes you may want to calculate it by yourself. Maybe you are comparing solutions, or you just want to know how big it will be.
My intention is to show how you could size your own solution in IBM SmartCloud Enterprise+ (SCE+) and understand some restrictions and benefits. This could also help anyone who is thinking about moving to cloud, but does not know where to start!
The first step is to understand your requirements regarding CPU, memory and storage. You can change these options during your journey to cloud. You also need to agree with the cloud terms regarding monitoring, backup, restore, maintenance, security and so on.
In most situations, the solution requirements size the solution in number of cores, memory and storage. The tricky part is knowing how to convert the number of dedicated cores to a comparable metric between dedicated hardware and cloud virtual CPU (vCPU).
My suggestion is to ask your hardware vendor about how much relative server performance estimate 2 (RPE2) the requested core, processor or machine can deliver. RPE2 is an international computer benchmark developed by Ideas International that we can use to compare hardware. For more about RPE2, click here.
With this information, you should understand the utilization expected inside the requested original box. For example, if the sizing solution requests two cores to be used at 60 percent on average, you should use only 60 percent or maybe 70 percent (using a 10 percent margin) of the original request in cloud. This way you can guarantee that you are using exactly what you need without waste and if for some reason you need more than that, you can increase and decrease any time you want.
You can start using something around 500 RPE2 for a virtual CPU (vCPU) for CISC (Intel) servers. With the number of vCPU required, you can check the sizes on the table below to discover the T-shirt size that best fits you:
Remember that the sizes already come with memory, so if you need 12 gigabytes for memory on your large 64 bit instance, you need only to include an additional four, since eight are already allocated to each 64 bit large instance or 16 to XL.
This also happens with storage size. The 64 bit large instance includes 192 gigabytes of storage. So, if your requirements are for 500 gigabytes, you should only include 308 additional gigabytes.
The general cloud idea is that you can build your solution like you’re using Legos, starting with some basic needs and increasing or decreasing the sizes as required—and only paying for your real utilization. If you need more information about IBM SmartCloud Enterprise+ (SCE+), connect with me on Twitter @odilon_junior.