How to set up networked Time Machine backups for a household

Apple’s Time Capsule base station combines a Wi-Fi hotspot, a network router, and a backup drive connected to Time Machine into a single box. This was also its downfall: if the drive failed or was corrupted, you had relatively few options. Apple stopped selling Time Capsule devices in 2018, and many readers still miss them.

You can fake a Time Capsule if you have a desktop Mac that’s always on and has a robust network connection. Some asides:

• You can use network attached storage (NAS), but not all NAS systems support Time Machine. I’ve also heard many stories of inconsistent performance.
• Your computer acting as a networked Time Machine destination does not need to be on all the time. But this means that the computer, when turned on, will spend more of its active time making backups, thus catching up when it is turned off.
• A Mac laptop can work just fine as a networked Time Machine destination, but if you take it somewhere else, put it to sleep, or disconnect it from the battery, backups can’t take place.
• A robust network connection is advised, i.e. connect this machine via Ethernet to your network rather than relying on Wi-Fi. If you use the latter, Wi-Fi works well, but it may cause congestion your network due to the intermittent high value of backup data.

Time Machine is robust enough that if it can’t backup immediately, macOS caches files that need to be backed up if they change between backup sessions. Then it does an automatic catch-up, using backups cached on an individual Mac to transfer them to Time Machine.

Here’s how to get started with networked Time Machine backups; I’ll go over these points after this overview:

• Get a drive large enough to store the entire potential content of all the devices on your network backed up to it, plus 50-100% more capacity for storing archives.
• Format this drive to APFS.
• Partition the drive if you want to reserve specific storage for each Mac instead of creating a large pool for all Macs on the network.
• Using sharing settings to enable Time Machine on the drive.
• Log in from other Macs to set up Time Machine.

Get a big disk and format it as APFS

If you add up all the storage required on your network and add 50-100% more, and it comes out below 2TB, you might consider an SSD for speed and quiet. The drive may be running a reasonable percentage of the time, and if you or someone else is working next to the computer that is the Time Machine destination, you will hear a hard drive (HDD) moving away.

That said, if your total needs exceed 2TB, 4TB drives are still quite expensive (more than double the cost of 2TB) and you either want to buy multiple 2TB drives or upgrade to a hard drive. Nowadays you can get very large capacity hard drives (12TB or more) for one song. (I chose to get a two-drive system and use RAID mirroring in order to have a second backup: each backup bit is written to both drives in the event of one drive failure. between them. You can find RAID systems from many companies, although they add to your cost.)

APFS has been the preferred Time Machine backup drive format since fall 2021 and I recommend using it. Follow Apple’s instructions to format your drive as APFS. This is a destructive process and you will lose all data on the disk, so copy it and make sure you have a perfect copy before erasing it in this case.

Partition the disk

With Time Machine, you have the option of either using one large storage pool for everyone and Time Machine creating individual backup destinations for each Mac, or partitioning the drive and having each computer on the network target a specific partition. I’ve seen problems (as have forum posters and readers) with the pooled method: Time Machine should automatically purge old snapshots as storage in pooled storage becomes full, but it doesn’t always seem to recognize that he must act.

Follow Apple’s instructions on APFS partitioning. Create a single container, then partition that container for the number you need.

Each partition dedicated to a specific Mac should use the 50-100% guideline above to define its size.

Configure sharing for Time Machine

I’ve found that using the process Apple describes doesn’t always work reliably, while sharing these volumes so everyone can read and write to them helps Time Machine. Instead, I do the following:

1. Create a new user on Mac offering Time Machine backups. You can follow the instructions in this article. The user does not need administrator privileges. I named this user “Network Time Machine” for clarity on my Mac.
2. On macOS Ventura or later, go to  > System Settings > General > Sharing and click on the i (info) icon to the right of the File Sharing article.
3. Drag each volume into the Share folders list. In turn, select each volume, click the + button at the bottom of the screen. Users lists and add your network user. Select Read write in the context menu to the right of this user’s name in the list.
4. Additionally, for each volume, Ctrl-click/right-click the volume name in the list of shared folders and choose Advanced options. Enable “Share as Time Machine backup destination”. You can set a maximum limit for backups, but this is not necessary if you are using the entire volume for Time Machine.
5. Click on Do.

Foundry

Foundry

Now, from each Mac:

1. In Finder, choose Go > Network, find the Mac and log in as a networked Time Machine user. (This shouldn’t be necessary, but I find that logging in first and storing the password in the keychain when prompted helps avoid Time Machine backup issues later.)
2. Go to  > System Settings > General > Time Machine.
3. Click the + sign to add a volume. The shared volume (grouped or specific to your Mac) should appear in this list. Select it and click Configure disk.
4. Next, you may be prompted to sign in to a user account, even if you’re already signed in to that account in Finder or with Time Machine.

Foundry

You can optionally use this process to configure encryption for the backup in the final step, meaning that the key you choose is the only way to unlock it later. If you choose to encrypt your networked Time Machine backup, be sure to store the key in a password manager. There is no other way to unlock the backup because the password is unrecoverable, even from the Mac backing up to a connected drive.

This Mac 911 article answers a question submitted by igamesnews reader Anton.

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