In the OEM I see at the "Area Summary" section: Top 5 worst performing area, see the image
What is this mean?
Russian Progress User Group
This means that you the data is going in the variable extent rather then the fixed one, Add the extra fixes extents on these area's and you are good to go
OEM uses the information from the _AreaStatus VST to identify the worst performing areas The percentage of area used is calculated from _AreaStatus-Totblocks _AreaStatus-Freenum values. If the percentage exceeds 80% (and the area is not either of Control Area or Primary Recovery Area), it is reported as one of the top 5 worst performing areas.
Thank you Ezaz!
Maybe I haven't had enough coffee yet this morning, but that metric is ridiculous. And useless. And worse, misleading.