Back Up macOS with Time Machine to a NAS Using GoMount

Time Machine is the easiest way to back up a Mac, but an external USB drive is not always practical. Backing up to a NAS gives you central storage, automatic wireless backups, and room to keep years of snapshots. With GoMount, the share is mounted automatically when your Mac is on the home network, so Time Machine can run without any manual steps.

This guide walks through preparing the NAS share, mounting it with GoMount, and pointing Time Machine at it. It covers both SMB and NFS shares and includes a fallback sparse-bundle method for stubborn NAS models.

Why Time Machine on NAS?

Storing Time Machine backups on a NAS has a few clear advantages over a local disk:

• Centralized backups. One NAS can back up every Mac in the house.
• Automatic and wireless. Backups happen over Wi-Fi whenever the Mac is on the home network.
• Large capacity. Add drives to the NAS as your backup history grows.
• Network resilience. Time Machine resumes automatically after sleep or a brief disconnect.

The most reliable protocol for Time Machine is SMB. Apple officially supports SMB for Time Machine since macOS Sierra, and most NAS vendors optimize their SMB stack for it. NFS can work, but it usually requires extra steps and is less forgiving with permissions. If you are unsure which protocol to choose, see our NFS vs SMB comparison.

Prepare Your NAS Share

Before configuring Time Machine, create a dedicated share on the NAS. A separate share keeps backups organized and makes permissions easier to manage.

General NAS requirements

• Create a shared folder named something like TimeMachine or MacBackups.
• Enable SMB and, if desired, AFP emulation or Bonjour Time Machine broadcast. Many NAS systems expose this as "Mac file service" or "Time Machine service."
• Create a dedicated user account, for example timemachine, with read/write access to the share.
• Disable recycle bins and snapshot replication on the backup share if you want to avoid double counting space.
• Reserve at least twice the capacity of the Mac's internal drive. Time Machine keeps local snapshots and a long history, so more space is better.

Synology DSM

On Synology, open Control Panel > Shared Folder and create TimeMachine. Then go to Control Panel > File Services > SMB and enable SMB 3. In the same panel, check Enable Bonjour service discovery and select the TimeMachine share so it appears in System Preferences automatically.

QNAP QTS / QuTS hero

Create the share in Control Panel > Shared Folders. Then open Control Panel > Network & File Services > Win/Mac/NFS, enable Apple Networking, and set the TimeMachine folder as the Time Machine backup destination. QNAP supports AFP and SMB; use SMB for modern macOS versions.

TrueNAS Scale

Create a dataset with a quota if you want to limit backup size. Then add an SMB share and set Time Machine to Yes in the share options. TrueNAS will advertise the share via Bonjour automatically when the SMB service is running.

Mount the Share with GoMount

If this is your first time using GoMount, start with the Getting Started guide to install the app and verify basic connectivity. Once the app is running, add a new mount:

1. Open GoMount from the menu bar and click Add Mount.
2. Choose SMB/CIFS as the protocol for Time Machine backups.
3. Enter the NAS address, for example smb://192.168.1.10 or smb://synology.local.
4. Enter the share name, for example TimeMachine.
5. Provide the dedicated user credentials you created earlier.
6. Add a network trigger rule so the share mounts automatically when you are home. A typical rule uses your home IP range, such as 192.168.1.0/24, or matches your Wi-Fi SSID.
7. Save the mount and verify it appears as connected in the menu bar.

By default, GoMount mounts the share under /Volumes/TimeMachine or a similar path. Open Finder and confirm you can create a test file in the share to verify write permissions. If write fails, double-check the NAS user permissions and that the share is not read-only.

Configure Time Machine

Once the share is mounted, tell Time Machine to use it:

1. Open System Settings > General > Time Machine on macOS Ventura or later. On older macOS versions, open System Preferences > Time Machine.
2. Click Add or Remove Backup Disk.
3. If your NAS advertises the share via Bonjour, it appears in the list. Select it and enter the credentials.
4. If the disk does not appear, click Other or Network Disk and enter the SMB path manually, for example smb://timemachine@192.168.1.10/TimeMachine.
5. Click Set Up Disk and, if prompted, enable encryption. Encryption protects backups if the NAS is ever accessed directly.

Time Machine will create a sparse bundle on the share named after your Mac and begin the first backup. The initial backup can take several hours depending on the amount of data and network speed. Leave your Mac connected to power and the network.

Manual Sparse Bundle (Optional)

Some NAS models do not advertise themselves as Time Machine destinations, or Time Machine refuses to use the share because it reports itself incorrectly. In these cases, you can create the backup bundle manually:

1. Find your Mac's hostname and hardware UUID. Run these commands in Terminal:

   hostname
   system_profiler SPHardwareDataType | grep "Hardware UUID"

2. Create a sparse bundle locally. Replace ComputerName with your hostname and MAC_UUID with the UUID:

   hdiutil create -size 500g -fs APFS -volname "Time Machine" \
     ~/Desktop/ComputerName_MAC_UUID.sparsebundle

3. Copy the sparse bundle to the mounted NAS share:

   cp -R ~/Desktop/ComputerName_MAC_UUID.sparsebundle /Volumes/TimeMachine/

4. Open Time Machine preferences and select the mounted sparse bundle. It should now be recognized as a valid backup destination.

If you want a larger or smaller backup container, adjust the -size value. You can grow a sparse bundle later with hdiutil resize, but shrinking is more involved.

Troubleshooting

Time Machine says the disk is read-only

This usually means the NAS user has read-only access or the share was mounted with guest credentials. In GoMount, edit the mount and re-enter the username and password. On the NAS, confirm the user has full read/write access to the share.

Backups are very slow

Check that you are using SMB 3 and not SMB 1 or AFP. Also verify the connection is on your local network; Time Machine over a VPN or relay will be slow. If you are on Wi-Fi, move closer to the access point or switch to Ethernet for the first backup.

Backups stop after the Mac sleeps

Make sure GoMount's keep-alive option is enabled for the mount. Also allow Wake for network access in System Settings > Battery so the Mac can finish backups while plugged in and asleep.

Time Machine cannot see the NAS

Bonjour advertisement may be blocked by a VLAN, subnet, or firewall. Mount the share manually with the SMB URL, or create the sparse bundle on the share as described above. You can also check our Getting Started guide for network debugging tips.

Next Steps

With Time Machine backing up to your NAS, your Mac is protected against drive failure and accidental deletion. To get even more from GoMount, explore these related guides:

• Auto-Mount NAS When Your Mac Comes Home — fine-tune network trigger rules.
• Manage NAS Without Finder — browse, copy, and search files directly in GoMount.
• NFS vs SMB on macOS — understand protocol differences for other mounts.