Storage Workload Concentration (SWC)

Sam Kirchoff

SWC is a representation of the facts about storage LUNs/Volumes. This is displayed in a way that allows you to quickly see what drives [LUNs/Volumes] are creating the most activity in the environment as well as their ratio to overall data capacity.

SWC is very similar, but has differences from Server Workload Concentration. You can real all about that here

SWC: Bubble Graph

As Live Optics collects the current environment it will understand the capacity and performance of each object. In this document an object will include any LUN, Volume, DataStore, or Internal Capacity disk mapped back to a storage array that donates to the overall capacity figure determined by Live Optics in the project summary.

SWC is simply a plotting of the relationship of those object's performance (IOPS) over capacity. The plotting of each bubble is slightly different than Server Workload Concentration. The 95th% is not used as the placement indicator, instead the Total % IOPS contribution is used. As an example, if the SUM(reads+writes) for the entire sample period showed that LUN A contributed 23% of all IOPS, then that bubble would show at the 23% marker on the vertical scale. 

Each of those objects are then plotted in a graph, much like the sample below, with the highest-performing objects on the upper far left and the lowest performing objects on the lower far right.


Therefore, the height of each “bubble” is representing the amount of IOPS in relation to all other bubbles.
Used Capacity of that disk is represented by the diameter of the bubble. The wider the bubble, the larger in capacity the disk.

The horizontal axis demonstrates all capacity from the environment. There is an arbitrary 20% capacity line drawn in the graph for the purpose of creating a calculation of what amount of IOPS fall into what amount of capacity. This is commonly referred to as Skew and can be calculated in various method. Live Optics will add up the total % IOPS of the bubbles (or partial bubbles) that fall on or to the left of the 20% line. Those objects total % and their capacity will define the concentration value. 

The additional attribute of Quality of Service is introduced by the color indicator assigned to each bubble. Green is a healthy average latency, yellow represents a potential area of concern, and red indicates a disk that potentially needs to be inspected. By no means are these colors a predictor of a problem. They are just a visual indicator of the facts.

StorageWC_B.JPG

Researching a Potential Problem
The Bubble Chart will become more insightful when the project has a higher number of objects. In a single picture you can see hundreds of objects and zoom/focus to the areas in which you wish to concentrate. 

The Server edition of this chart uses application level latency responses times. Server values actually include the Storage response in the total response time. However, the Storage version of the chart will represent latency only on the array and the legend reflects millisecond values found acceptable for Storage response times.

As an example of this, if you have a server with a 20ms total response time and a storage array with a 2ms total response time, then 18ms of latency is attributed to something other than the storage array.  

The WC Bubble chart can appear too densely populated if the environment has hundreds of disks or has little variation in the performance of each bubble. As seen at the far right of the example above, when there are many similar performing bubbles. The graph can produce a “snake” like effect which makes it hard to isolate a bubble. To gain visibility to dense regions of bubbles the chart can be zoomed with the graph controls below the chart.

Each bubble can be “hovered over” to see the objects name, performance, capacity, and role.

Bubbles marked with a gray color represent a disk that does less than 100 IOPS in either reads or writes. Low-IO disks can skew latency averages and these disks can be ignored. You can read more on the Live Optics support site: KB: 78846377 

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