[Samba] No luck with Time Machine and 4.23.5

[Stefan Bethke]

On 30. Jan 2026, at 09:48, Stefan Bethke via samba <samba at lists.samba.org> wrote:
> 
> I have a few Macs backup up to my Samba server, and this has worked without a hitch for many years.
> 
> While trying to restart a backup on a machine where Time Machine was unhappy, I decided to wipe the share and start over fresh. Since then, Time Machine gets stuck after about 3.8 GB, never progressing any further. Another Mac is happily backing up to the same server.
> 
> The server is Debian Trixie with the backport packages (2:4.23.5+dfsg-1~bpo13+1), the Mac is running 26.2.
> 
Lots of informatin trimmed, see the archive for all details: https://lists.samba.org/archive/samba/2026-January/252570.html

I've just tested creating a sparseimage manually to see if having it extend is the main culprit, but it seems Time Machine is doing something special. I cannot reproduce the error with a plain sparseimage.

What I've done:
1. Mount the volume locally through Finder.
2. cd /Volumes/Time\ Machine\ Backups
3. hdiutil create -size 1000g -fs apfs -volname test test.sparsebundle
4. hdiutil attach test.sparsebundle
5. cd /Volumes/test
6. dd if=/dev/random of=x bs=1m count=10k status=progress

dd completes successfully, and a du on the volume shows that 10G are being used.

When Time Machine backs up, the size never gos above 4G. The local log is filled with:

attrVolumeWithMountPoint 'file:///Volumes/.timemachine/REDACTED/92D967CA-8376-413C-8E84-694D4706AA30/Time%20&Machine%Backup/' failed, error: Error Domain=NSPOSIXErrorDomain Code=13 "Permission denied"

This was from a completely empty volume, and Time Machine was set up fresh.

Is there some option that I need to set? From looking at the bug/patch https://bugzilla.samba.org/show_bug.cgi?id=15926, it seems to be that it should just work?


Stefan

-- 
Stefan Bethke <stb at lassitu.de>   Fon +49 175 3288861