I thought I would take a moment to write an article on an exercise that happened to me recently. Recently, I was requested to see if a new project could go on an existing VxRail/vSAN cluster. My trusty tool I like to go to for a quick answer, pretty visuals, and costs matrix is vROPs. I ran the what-if for HCI and everyone was happy. I did get the request to explain how vROPs came to the projected numbers. However, my reply of it’s vROPs math was sufficient. Below you will see the math formulas I used to reverse engineer vROPs Math. Below my math formulas is the step by step how to in order to produce the report.
vRealize Operations Math:
As stated above. I was requested to reverse engineer the math so my leadership could understand how vROPs came to these numbers. I hope this helps.
vRealize Operations Memory Math
Cluster setting is annual growth of 12% Current used space is 2.34TB, I am looking to add 754GB of memory at 70% utilization on Day 1 with a growth rate of 5%
2340×1.12=2620 —> projected utilization over next year prior to workload add
754x.05=37 —> growth
791x.7=553 —> 70% utilization
553+2620=3173 —> peak
I will be the first to admit I am my math is off by 43GB so my educated guess is that has to do with reporting current utilization vs what it may have been last time vROPs polled data.
vRealize Operations vSAN Math
Cluster setting is annual growth of 13%. Current used space is 51.04TB, I am looking to add 806GB of storage at 70% utilized on Day 1 with a growth of 5%. Plus, Dedupe/compression is enabled on this cluster at 1.3:1 ratio.
5104×1.13=5762 —-> projected utilized over next year prior to workload add
806x.05=40.3 —-> 5% growth over next year
846×2=1,692 —-> Raid-1 overhead
1692x.7=1184.4 —-> 70% utilized
1183/1.3=910 —> Post dedupe/compression
910+57620=58.53TB —> Peak utilization
As you will see below when we expand the view details section under Private Cloud: Datacenter the numbers will match up
Step by step workload report:
Home > Optimize Capacity > What-if Analysis > Workload Planning: Hyperconverged > Add VMs
You’ll want to give it a name, I normally select the name of the project or the application that is making the resource request.
In location you need to select your vCenter you want to deploy the workload in. Then select the cluster within the vCenter.
You have two options.
Option 1. Import from existing VM – this allows you to select VMs that exist in your environment assuming you will be deploying like for like VMs.
Option 2. Configure – This is the option I use majority of time because it allows me to get granular on net new workloads. Once you fill in the values as granular as you desire you can click Run Scenario and get your results.
If you click view details it will expand out into greater detail:
As you can see if you don’t need to reverse engineer the math this process should go quickly. vROPs is a powerful tool and I am a fan of all the what-if scenarios. As always, I hope y’all find this helpful.