|Article Number: 503443||Article Version: 3||Article Type: Break Fix|
VMAX3 Series,VMAX All Flash,Unisphere for VMAX 8.4
Headroom calculation shows a smaller than expected value.
Unisphere for VMAX issue: Under circumstances where there is a small amount of IO to the array, and the IO profile is such that the reads and writes are in large block counts (64KB IOs or greater), the Workload Planner (WLP) algorithm within Unisphere is incorrectly calculating the Headroom value for SLO and/or Workload profiles when queried.
As the workload increases in the array over time, WLP will be able to more accurately.
A fix has been developed and will be incorporated into Unipshere for VMAX version 9.0. Version 9.0 has a planned availability of early 2018.
Until version 9.0 is available, it's advised to use the SRP Capacity and Demand Reports inside the Storage Groups Dashboard to calculate available space.
What is Headroom?
Displays the space available for a particular service level (SLO) and workload combination, if all remaining capacity in the system's internal SRP(s) was on that type. For external SRPs, Headroom information is not displayed.