Thats tricky... that is an indication of how much usable capacity is left for a CPG to grow, based on raid over head. It is looking at the raw PD space free, and converting that into usable space, per CPG. It is key to understand that if you have multiple CPGs pulling raw PD space from the same place, that the free space is shared. Here is the official verbiage on the report:
Quote:
The growth space is calculated for each CPG independent of the other CPGs. If multiple CPGs grow from the same or overlapping set of chunklets, then the aggregate growth space for the CPGs shown in this report is overstated. For example, if two CPGs allocate space from NL chunklets, growth space for each CPG is calculated assuming all the NL chunklets are available to each CPG.
The CPG growth space is calculated without considering the CPG limit, and may thus be higher than the limit. The actual CPG growth will be limited by the CPG limit, if it is set.