I recently received a new external hard drive containing data from a failing drive - the data was simply copied from the old, failing drive to the new. At the top level of the drive, I have a folder named "$Extend" - from carrying out some initial research, it appears that this folder is related to the NTFS file system and in the majority of cases isn't visible when viewing directory listings via Windows Explorer.

IN this case, I'm presuming that the presence of this folder is due to the fact that it was copied from the old, failing drive to the new as a regular folder - which is why it's the first time that it's now being detected by Windows Explorer. In this case, is it safe to assume that Windows has created another duplicate (albeit hidden) folder with the same name at the time the replacement drive was formatted - and as a result this folder from the old drive can safely be deleted? I'm aware that typically it's not physically possible to create two files/folders with duplicate names, but am also aware that this is a file system directory - so wasn't sure if it was treated any differently.

  • Are you sure the new disk is in fact NTFS and not exFAT? Jul 7, 2021 at 20:19

1 Answer 1


Although according to Wikipedia NTFS the $Extend folder has appeared in Windows 2000, I haven't seen this folder in many years now.

So, first, I think this file is an old remnant from an older system.

Second, Wikipedia says that it's used more by some running applications rather than by Windows itself.

My opinion is that whatever relevance this folder had on the original system (if it had any), it's no longer relevant on the new copy.

  • 1
    It exists on all NTFS filesystems to this day, it's just literally invisible via regular file operations, so not seeing it is rather normal. Unlike the VMS equivalents. Try fsutil file layout 'C:\$Extend' on any Windows system (with single-quotes for PowerShell) or ntfsls on Linux. The "used more by applications" is mainly about Usn Journal, which has a dedicated API for programs to access it. Jul 7, 2021 at 20:18
  • @user1686: Result of the fsutil command: "Error: The filename, directory name, or volume label syntax is incorrect". In fact, the fsutil file command has no documented layout parameter, although it's still in the help issued by the command itself.
    – harrymc
    Jul 8, 2021 at 8:06
  • Make sure to actually quote (or not) the filename correctly. Here's it working in PowerShell. Here's it working in Cmd. (I borrowed a coworker's computer to make sure it's not a fluke.) The command exists; it gives results; if the docs are wrong, tell that to MS. Jul 8, 2021 at 9:00
  • @user1686: As I said, the $Extend folder doesn't exist on my new computer and hasn't been seen by myself for quite some time. The explanation might be that I do not install the applications that use it. But my answer still stands: It's not a required part of NTFS, and as testimony I bring my hard disks and every external disk of mine that I looked at. So for me, it can be deleted without negative consequences.
    – harrymc
    Jul 8, 2021 at 9:04
  • I have one on my Windows 11 machine (disk formatted with Windows 11 install)
    – Joshua
    Jan 11 at 19:20

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