New
#41
What I meant to convey was that in order for your SSD controller to make use of that set aside 10%, it has to be unallocated space on the same physical SSD. By allocating that 10% space to a partition and drive letter, it is no longer available to the SSD controller to use.
From Seagate:
"Some SSD manufacturers provide software tools to allow for over-provisioning of drives by the user. Actually, even without special software, any user can set aside a portion of the SSD when first setting it up in the system by creating a [system, user, data, etc.] partition that does not use the drive’s full capacity. This unclaimed [unallocated] space will automatically be used by the controller as dynamic over-provisioning."
It seems the term "over-provisioning" is getting over-used ... to describe several methods of providing unused, unallocated SSD space to improve performance.
BTW, WinDirStat has not been updated since 2016-09-14. My choice would probably be TreeSize Free, V4.2.2, 14 Aug 2018