Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

It's my understanding from many years ago, that it is imperative to reboot after defragmenting . Is this still true for an external drive? I'm guessing that this would hold true for another partition as well, i.e., a data partition. Thank you for your time to anyone answering.

share|improve this question
Why would it be imperative to reboot after defragmenting?! – David Schwartz Jul 15 '12 at 3:54
The only reason that I can think of for rebooting after defragmenting would be to reset the next-free-cluster pointer so that the next write is at the start of the free block instead of somewhere in the middle/end. – Synetech Jul 15 '12 at 4:00
Is this even relevant on a data drive? Won't chkdsk do the same thing? Or is it related to forcing chkdsk to run at reboot? – user3463 Jul 15 '12 at 17:36
Yes it is relevant. I just performed a defrag to free up a large chuck of free space, but if I then create a folder, instead of the folder being created at the beginning of the free block, it is created in the middle, thus breaking the large free block into two chunks (which of course could drastically increases the chances of future fragmentation). chkdsk has no effect on the next-free-cluster pointer. I’m looking for a way to force the drive/OS to reset the pointer, but so far, rebooting seems to be the only effective solution. – Synetech Oct 27 '12 at 21:18

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.