Laptop with Windows 10 Pro v1511 x64, with 512 GB Samsung SSD 850 PRO as system drive.

In an attempt to overprovision space on the SSD, I just shrunk the system partition from about 475 GB to 400 GB. While Samsung Magician recognizes the unused space as overprovisioned, it's my understanding that the space must be explicitly marked as unused using the TRIM command for overprovisioning to work as intended.

Does Windows automatically trim unpartitioned (unformatted) space, including after shrinking a partition? I vaguely remember reading that Windows trims the space freed after deleting a partition, but I'm not even sure if that's true, either.

  • if it is unpartitioned space, no write/deletes occur to it, so thee is no need for a TRIM. Jan 24 '16 at 6:10
  • 2
    The drive does need to know that the space is unused. Otherwise, it can't use the unpartitioned space for overprovisioning.
    – bwDraco
    Jan 24 '16 at 6:16
  • Technically only a blank SSD can be said to be unpartitioned. If there is a (formatted) partition, the unused space is said to be unformatted.
    – jiggunjer
    Jan 24 '16 at 9:09

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