Avoid MacOS Time Machine issues with Ubuntu SMB by Separating Users

Using Time Machine along with SMB shares seems to cause an issue when the backup runs the other SMB shares stop working. What is likely happening is MacOS is locking the files as it starts the backup to avoid read write problems.

Separating the users, as in having one SMB user for files sharing and a second for Time Machine seems to solve the issues.

Fortunately, setting up an SMB share for Time Machine is pretty straightforward and developer Marinus Klasen has a great guide. I’ve simplified what is needed an added it below at the bottom. General steps.

1. First, create the users and set up the disks on Ubuntu. Add 2 SMB users (guide on that below.)
2. Update the Ubuntu’s SMB settings.
3. Set up Time Machine on MacOS before connecting to SMB shares. The share you’re looking to use should show in the list.
4. Connect to your other SMB shares and go!

There’s a great quick guide on ask Ubuntu about adding a CLI only SMB user on Ask Ubuntu.

## For TimeMachine Config ##
# Fruit global config
  fruit:aapl = yes
  fruit:nfs_aces = no
  fruit:copyfile = no
  fruit:model = MacSamba

[timemachine]
   # Load in modules (order is critical!)
   vfs objects = catia fruit streams_xattr
   fruit:time machine = yes
   fruit:time machine max size = 1.5T
   comment = Time Machine Backup
   path = /TimeMachine (CHANGE THIS)
   available = yes
   valid users = timemachine (Maybe don't permit other SMB users.)
   browseable = yes
   guest ok = no
   writable = yes

Ask Ubuntu

Updated and Retried with Ubuntu 25.04 and MacOS Tahoe 26.0.1: 10/23/25