Which VMs need more resources?

You can reduce the following resources from a VM:

  • CPU
  • RAM
  • Storage

Network isn’t something you can reduce, but you know that already 🙂

You can check which VMs need more resources by building a dashboard like the one below. It’s a simple dashboard, which you can customize and enhance. It lets you reduce the resources independently.

I’ve marked the above dashboard with numbers, so we can refer to them:

  1. This is a table that lists all VMs. It’s sorted by the highest 1-hour average of CPU Demand and RAM Demand. The table also lists the VM CPU and RAM configuration, so you can see if the VMs are small or large. It also shows the cluster the VMs are located. The table is sorted by the highest CPU Demand. I’m showing both CPU and RAM in a single table. You can clone the view and split them if that suits your operations better.
  2. This is a table that lists all VMs, but focusing on storage only. With storage, we do not have the complexity of checking peak utilisation. We simply need to check the present situation.
  3. This lists the Top-15 VMs with highest CPU Demand and RAM Demand in a given period. The list is now split, as they can be different VMs. Do not that Top-N widget will average the number over the selected period. A VM with cyclical workload may not show up. The Top-N is complemented with a distribution chart. Select a VM from the Top-N, and you can see where the VM utilisation is.
  4. The distribution chart helps you see if the VM is really under resources or not. The 95th percentile is marked with a vertical green line. You expect that line to be at 100%, indicating that the VMs hit 100% utilisation frequently. If the 95th percentile is at a low number, and you do not see the number 100 in the x-axis, that means the VM is not under resourced.
  5. Storage is easier, as we can simply use the last data. As a result, we can show a distribution of all the VMs. We use a heat map as it can show 2 dimensions. Every VM is represented as a box. The bigger the box, the more storage the VM is configured with. The color indicates if the VM use it.
    • 0% = Black. Wastage
    • 10% = Green. Balanced usage
    • 100% = Red. Need more space!

The CPU and RAM have limitations. For example, they may show high utilisation during AV backup. You want to ignore those period. At this moment, the only way is to plot the high usage over a line chart. We use Log Insight for this. The chart below shows VMs that hit high CPU usage in a given period. Every time a VM hits high CPU usage, it will show up here. As you can see, there are only 4 VMs that hit high CPU usage. All other VMs do not need more CPU.

The above is an example from a healthy environment. What about an environment where a lot of VMs are under-sized? You expect to see lots of alarm! That’s what you have below

Hope the above is useful. If not, drop me an email.

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