or How I learned to like The Workload Concentration Bubble 

As an avid user of live optics to analyse environments for sizing, I was recently discussing the outputs with a peer, I realised there was a lot more to this particular graph than at first appears.

For those that don’t know, Live Optics is a free online tool by Dell to collect and analyse data about your IT workloads and environment – www.liveoptics.com . It allows you to create some really great graphs of your workloads in Windows, VMware, Linux, UNIX. You can run it on non-Dell environments as well.

One graph that appears on the executive summary report is the Workload Concentration Bubble. 

This is basically a snapshot of the performance your disk system.

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I really like the Workload Concentration Bubble (WCB) graph, because in one view you can see the multiple items of data about the disk system. Each circle represents a Disk (or LUN) and shows the following:

  • Quantity of disks (number on graph)
  • Each disk is first sorted by its 95th percentile IOPS number from highest to lowest and its performance plotted in the y axis
  • Relative Capacity (size of the circle)
  • Latency or QoS (colour of circle)
  • Distribution of capacity (position in x axis) 

Let’s delve in the example above for some assumptions/analysis:

  • There are 19 disks (number of circles)
  • They range in size from 30GB to 3TB
  • 20% of the capacity does 50% of the work
  • The most performing disk – the Red one – (@ 1200 IOPs) also has latency > 20ms
  • The second most performing disk – the yellow one – (@ 800 IOPs) also has latency > 10ms 

The big thing to look for is any yellow or red circles as they do indicate a potential disk IO bottleneck. A little bit more investigation will be required (Live Optics has many more graphs you can drill down on), but I would look at SSDs or NVMe as possible solutions. If we are having latency > 20ms at 1200 IOPs then spinning disks are probably not the best answer. 

So, in summary, a good quick overview of the disk system performance and my first go to when looking at designing Storage and Hyper Converged solutions.