Dell PowerVault ME5 Series Administrator's Guide

Reading the graph

The graph contains a line that reflects the capacity and a line plot for each selected workload.

• When graphed elements are above the SSD capacity line (or if there are no SSDs), data is spread over more capacity in the total system than could be serviced by the SSD capacity. The graph can give you a target SSD size to consider using.
• When graphed elements are below the SSD capacity line, there is adequate SSD capacity for hot data and you're receiving good value from your SSDs.

Interpreting this graph requires you to balance your expectations of cost versus performance. For example, you might be willing to have a couple of days where peak usage is far above the capacity line because it is acceptable to have slower performance during these times, given the cost. Or you could design your system to perform well during those times so the system has good I/O performance at all times.

Cumulative heat map data can also be useful in support case analysis. For information, see Downloading system heat map data.