I use a Synology NAS that has full Linux based user rights control and I want to setup a root shared folder called backup where I'll save backups from different technologies: Time Machine and Windows File History. Let's say I have the following structure:

  • Ana: uses Time Machine in a MBA
  • John: uses Windows File History in two different computers
  • Mark: uses Time Machine in a MBP

Time Machine backups are stored in a folder <computer-name>.sparsebundle and File History in a folder <windows-username>/<computer-name>, so my backup folder would have:

  • /Ana's MBA.sparsebundle
  • /John/PC1
  • /John/PC2
  • /Mark's MBP.sparsebundle

How can I configure the folder backup in a way that each users only sees their own folder and of course are blocked from R/W other users backups folders. Each user would need to be able to write inside the root folder backup so they would be able to create their Time Machine/File History folder for the first time and start using it for backup storage.

So, is it possible to achieve, or at least something similar?

  • Why not use a separate share per user?
    – GnP
    Commented Sep 4, 2016 at 1:10
  • Sadly I can't because Synology DSM only allows Time Machine clients to target Shared Folders like backup and I'd like to maintain the same logic for all backup technologies, aka, I don't want to have rsync/File History inside home folders while Time Machine backups inside shared folder backup.
    – JChris
    Commented Sep 4, 2016 at 1:17

2 Answers 2


set the sticky bit on /backup (that's how /tmp works)

chmod +t /backup
chmod ugo+rwx /backup
  • huh? the sticky bit blocks that unless the files are created with lax permissions.
    – Jasen
    Commented Dec 21, 2016 at 1:04
  • Heh, misread of mine. Sorry for that.
    – grochmal
    Commented Dec 21, 2016 at 1:55

The best way to solve this would be to create the initial directories by hand and then set the permissions such that only user(s) that need to access that directory can.

This does mean that before the first run of a backup a small amount of manual setup is required.

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