Evaluation

As StorMan’s storstat interface is providing counters and sampled metrics in conjunction with the time stamp representing the absolute collection time for the statistics. The calling application has to calculate and normalize the values to obtain the metrics per second.
This can be achieved by periodical calls in time intervals (t_n, t_m) calculating the rates for the delta = t_m - t_n.

1. To calculate the IO and MB values per second please use the following method:

                              delta(ReadIOs)
   ReadIOs per second = ——————————————————————————
                         delta(statisticTime) [s]

2. To calculate the average read (or write) times for ETERNUS DX/AF please use the following method:

                            delta(SampledReadsTime)
   AverageReadTime [μs] = ————————————————————————————
                            delta(SampledReadsCounter)

                             delta(SampledWritesTime)
   AverageWriteTime [μs] = ————————————————————————————
                            delta(SampledWritesCounter)

An evaluation tool has to assure to get statistical data at least once during one sample interval (default values: 3 min for ETERNUS DX/AF).