On 12/22/2025 at 9:13 AM, Rafaqs said:

[SOLVED] Time Machine on Unraid 7.2.3 + macOS Tahoe: Native SMB failures vs. Docker Success

Hi everyone,

After 8+ hours of troubleshooting a "The backup disk image could not be created" error on my M3 Max MacBook Pro (macOS Tahoe 26.2), I wanted to share the findings that finally got my backups running at 10Gb speeds.

My Setup:

• Unraid: 7.2.3 (Samba 4.21.3)

• Client: MacBook Pro M3 Max (macOS Tahoe 26.2)

• Network: 10Gb SFP+ (Unifi infrastructure)

• Hardware: i5, 64GB RAM.

What DID NOT work (Native SMB):

• ZFS Pools: Even with vfs_fruit and Enhanced macOS interoperability enabled, the backup failed during the "Creating disk image" phase.

• XFS Dedicated Disks: I formatted a dedicated 6TB XFS drive to test if ZFS was the culprit. It still failed. The native SMB service in Unraid 7.2.3 seems to have a metadata handshake issue with the latest macOS version that causes immediate timeouts.

The Solution: Time Machine via Docker The only 100% stable solution was bypassing the Unraid native SMB service and using the timemachine-samba Docker container (mbentley/awlx). This worked perfectly on both my NAS units:

• NAS 1: Running on XFS.

• NAS 2: Running on ZFS.

Crucial Steps for 10Gb Stability:

1. Hardware Fix (Syslinux): For 10Gb cards, I had to add pcie_aspm=off pci=noaer to the Syslinux configuration to prevent PCIe bus errors and log spamming during heavy transfers.

2. Dedicated IP (Custom br0): Assign a unique IP to the Docker container (e.g., .220). This prevents port 445 conflicts with the Unraid host and provides a "clean" Avahi/mDNS broadcast for the Mac.

3. Container Path Alignment: This is vital. You must edit the Docker template so the Container Path matches your TM_USERNAME (e.g., /opt/youruser). If they don't match, the Docker will write data into the docker.img vDisk instead of your HD, filling your system disk in minutes.

4. Permissions: Run chown -R 1000:1000 /mnt/user/your_share/ via terminal before starting the container to ensure the internal Docker user has write access.

Conclusion: If you are on high-end hardware and the latest macOS, don't waste hours fighting with Native SMB Settings or SMB Extras. The Docker isolation provides the specific Samba environment the Mac expects, regardless of whether your backing store is XFS or ZFS.

Hope this helps someone save a day of work!

You did indeed save me a day of work, thank you for this solution. Using the new tailscale feature of Docker containers, I was also able to expose this privately on my tailscale network instead of giving it a LAN IP. This is working better for me than the Unraid implementation anyway. Probably not gonna go back to the old way even after it's fixed. Thanks!!

I encountered the same issue as when starting a new Time Machine (TM) backup: if you have an existing backup, everything works fine. I want to thank bmartino1 for clearing the field, I agree with him: the problem lies deep within the Unraid OS.

I installed the Docker Samba server, and it works flawlessly. In macOS 26.2, the Time Machine control panel immediately recognizes a share on the network that supports Time Machine without the need to mount the share first, which is required when using Unraid shares.

I suggest changing the share name (Advertised Hostname) to "TimeCapsule" and also updating the extra parameter in the advanced view to --hostname TimeCapsule. Using "TimeMachine" as hostname and share mount can create confusion.

Finally, I noticed several errors in the Docker log due to incorrect settings. These should be configured as follows:

SMB vfs objects: fruit streams_xattr

SMB fruit:nfs_aces: no

Additionally, I set the following two settings. They are debatable, but they work great for me:

Set Permissions: false

SMB Inherit Permissions: yes

As for the Docker icon URL, it didn’t work for me, but I found an alternative link with a nice logo.

https://cdn.jim-nielsen.com/macos/1024/time-machine-2019-09-25.png?rf=1024

Thanks

8 minutes ago, Alfredo said:

the problem lies deep within the Unraid OS.

Yes, see https://forums.unraid.net/topic/195091-time-machine-backup-disk-image-cannot-be-created-on-zfs-pool/page/2/#findComment-1597628

On 1/5/2026 at 4:35 PM, JorgeB said:

Yes, see https://forums.unraid.net/topic/195091-time-machine-backup-disk-image-cannot-be-created-on-zfs-pool/page/2/#findComment-1597628

Any ETA when will be fixed ?

I hope for next release, but don't have any new info.

Same issue here. Very annoyed Lifetime customer. This broke my whole multistep backup strategy. I refuse to use the docker-based workaround given it makes things more complicated and rely on third-party software. TBH I expect the unraid team to fix this e. g. by downgrading Samba and do a bugfix release or find another solution, because this broke existing functionality without any warning.

1 hour ago, saber-raider said:

I refuse to use the docker-based workaround given it makes things more complicated and rely on third-party software.

You don't need to, you can also downgrade to 7.1.4, TM should work fine there.

I am on 7.2.3 . This would be a downgrade over multiple versions, right? Isn't this a risky endeavor?

1 hour ago, saber-raider said:

This would be a downgrade over multiple versions, right? Isn't this a risky endeavor?

Should be fine, the kernel and OpenZFS are still 6.12.x and 2.3.x respectively, so it's not a big change.

I have the same problem, please fix it! I dont want to use custom images :/

I was able to install the Docker solution, give it a custom network IP, and configure the mount point fine. I see the mount point and changed ownership to user:group 1000.

The Mac sees the volume as a Time Machine destination (and I can even mount it as a volume and write files/folders to it) but when attempting to configure it in the Settings - Time Machine panel I get:

The selected network backup disk does not support the required capabilities.

Please be sure Time Machine capabilities are enabled on the server for this volume or choose a different network backup volume.

I double-checked and don't think I missed a step. Any idea why this isn't working from a Mac running 15.7.3? Not Tahoe. I've tried mapping the Time Machine volume to both a btrfs and zfs pool.

3 minutes ago, RandoUser said:

Any idea why this isn't working from a Mac running 15.7.3? Not Tahoe. I've tried mapping the Time Machine volume to both a btrfs and zfs pool.

The docker has its own support thread (click the docker’s icon and select “support”). I would suggest posting any issues there. It’s typically well supported.

Is there an actual acknowledged bug open for this? Anyone have a link. I don't mind waiting if I know what bug I am waiting on the be fixed?

17 hours ago, locmer said:

Is there an actual acknowledged bug open for this?

There's no bug report, but LT is aware of the issue:

https://forums.unraid.net/topic/195091-time-machine-backup-disk-image-cannot-be-created-on-zfs-pool/page/2/#findComment-1597628

Please update to 7.2.4 and retest, it should finally be fixed there.

7 hours ago, JorgeB said:

Please update to 7.2.4 and retest, it should finally be fixed there.

I was having lots of trouble with Time Machine on 7.2.2 & 7.2.3 (didn't try older version) where I wasn't able to get Time Machine to work at all.

It seems to be working on 7.2.4 now!

Confirmed working on 7.2.4 - I'm now able to start a Time Machine backup!

1.2% copied, let's see if it finishes! I wasn't able to get this far before on the older versions of Unraid.

Thanks everyone, especially @JorgeB and LT!

update: backup finished successfully. All working!

Edited February 25Feb 25 by 8GDWLbk9HRKtlJJvaiFG

This is working for me in 7.2.4 as well! Glad to see this finally fixed!

Thank you for fixing this!

It was very odd because I had 3 MacOS devices working just fine, but the newer M4Pro one did not.

I'm happy to have a network TimeMachine again instead of a USB physical one.

Finally! So happy that this has been fixed. Just don't know why it took so long. Hope something fundamenal like that doesn't break again anytime soon.

8 hours ago, saber-raider said:

Hope something fundamenal like that doesn't break again anytime soon.

It is a Samba bug, it's supposed to be fixed in both Samba 4.23.4+ and 4.22.7+; it turns out it's only fixed in the 4.22 branch, so LT had to downgrade from 4.23 to 4.22.

Was having this same issue after an upgrade and upgrading to 7.2.4 (With the downgrade to Samba) fixed the Time Machine issue for me.

I am on 7.2.4 ZFS and Tahoe 26.4, I am not able to use Time Machine backup. Everything has been working before and now I have no idea which of all of the fix options I should use?

I shouldn't need to run Docker to be able to do a TM backup.

Able to mount it on Mac and add it as a backup, but once I start the backup, it fails immediately

Any ideas?

Update: Just tried to set up recommended Docker, exactly the same result...

Edited April 6Apr 6 by 6103242

8 hours ago, 6103242 said:

I am on 7.2.4 ZFS and Tahoe 26.4, I am not able to use Time Machine backup.

TM has been confirmed fixed in 7.2.4 by multiple users, so you are likely having a different issue. Recommend creating a new thread in the general support forum and posting the diagnostics.

6 hours of back and forth with LLMs (F***) and this is what fixed it natively on Unrain TM.

Unraid 7.2.4 - MacOS Tahoe 26.4

sudo /usr/libexec/PlistBuddy -c 'Add :UNRAID_IP_HERE bool true' '/private/var/root/Library/Group Containers/group.com.apple.NetworkAuthorization.ServerMarkers/serverMarkers.plist'