Mounted folders disappear in shared folders

If you have either a Mounted Volume or Junction Point that maps to the root of a volume you may find that this folder intermittently disappears when accessed through a shared folder.

A Mounted Volume is a volume mounted in an NTFS folder typically created using the Disk Management MMC console

A Directory Junction point is a folder referral that is typically created using MKLINK.exe /J

The problem is caused by the SMBv2 Client Redirector Cache and has been acknowledged by Microsoft as a known problem in the following operating systems:

  • Windows 7
  • Windows Server 2008
  • Windows Server 2008 R2

The problem can easily be observed by performing the following actions:
Note, all actions assume you are using one of the above operating systems in all cases

  1. Access a remote file server share that has a mounted volume folder within it
  2. Access the mounted volume folder
  3. Go back to a folder above the mounted volume, or access the remote file server share again
  4. The mounted volume folder should now be hidden
  5. The mounted volume folder is still accessible using the full path

The following workarounds can be used to remove the problem:

  1. Set the following registry key to disable caching
    Setting this registry key removes some of the performance improvements in SMBv2 and can potentially increase load on the file servers
    DWORD Name:DirectoryCacheLifetime
  2. Change the volume mount point or junction point to map to a directory within the volume instead
  3. Disable SMBv2 which disables the caching feature introduced in SMBv2
    Not Recommended.

Microsoft have released a knowledge base article to address this specific problem:

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