Wireless backup help wanted

A few months ago I upgraded my 2018 MacBook Pro to a current MacBook Air. The 2018 MBP was going into kernel panic once or twice a week, and I was nervous about relying on it as my daily driver.

But the 2018 MBP still mostly works, and I’ve been thinking about configuring it as a wireless backup. I could just hang an external drive or two off it, and I’d be good to go, right?

Obviously, if the thing does fail permanently, then I’ll need an alternative for backups, but even then, I’d have the already-created backups.

Is there anything wrong with this plan? What else do I need to know or consider? This is my first wireless backup; until now I’ve relied on attached drives and BackBlaze.

I did this with a 2014 Mac mini using Time Machine to back up my main Mac (an M1 MacBook Air) via Apple File Sharing over the network, sometimes wired and sometimes wirelessly. It worked for a while. When Time Machine quit, as it always has for me, instead of starting over, I switched to running hourly Carbon Copy Cloner backups to a spinning disk drive connected to my MacBook Air via the Thunderbolt / USB hub built into my big external monitor. I like not having to deal with a shared drive on another Mac for my backups.

Consider how much data you’d be using doing this.

Even though all of my TV and music comes into my apartment via the internet, I seldom go over half my data allotment each month.

When I tried running Time Machine over the network I blew right through my data cap.

If you are talking about backing up locally, then I recommend Chronosync with ChronoAgent. You would install Chronosync on the Mac to be backed up and CA on your 2018 MBP.

@karlnyhus You found Time Machine over Wi-Fi to be unreliable then, and switched to an attached disk? I’m trying to avoid mounting and unmounting an external disk.

@acavender I would be running the Time Machine backup over a local area Wi-Fi network. How would that affect my data cap?

@WayneG I will look into Chronosync. Thanks!

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I’ll admit that networking isn’t my strong suit, so I may not fully understand what you mean.

But in case it’s helpful: what I did was hang an external drive off my base M2 Mac Mini. I set that up as a share, then told Time Machine on my MacBook Pro to use it as a backup drive. Both machines were on my home network any time Time Machine ran.

That setup blew right through my data cap.

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I understand that might be an issue for you. However, I already disconnect my MacBook Air from the big monitor at night and often for a while first thing in the morning.

The external backup disk drive connects via a USB cable to a Thunderbolt port on the display monitor which, in turn, connects from the monitor’s other Thunderbolt port to the MacBook Air with a single Thunderbolt cable, which supplies data and power. Your newer MacBook Air might have a separate power supply and MagSafe connector.

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Many people have found Time Machine unreliable over Wi-Fi. Any reason you can’t connect via Ethernet? My iMac does TM to a share on a Mac Mini. Has worked well but it’s all hardwired. My primary backup method is CCC.

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That setup was entirely on a local network and should have had no influence on your ISP data usage. Unless you use Tailscale or a VPN service to connect your devices virtually over the Internet, Time Machine does not work over the Internet; it only works locally.


Last time I tried back in up Time Machine via WiFi it seemed to work fine. However, I needed to do a roll back my OS at one point as I got some issues with something I installed. The installer failed and wouldn’t work when I retried as it said the data was corrupt.

After that I’ve never used WiFi again. Luckily I also had a slightly older but usable CarbonCopyCloner backup at the time, and that saved my data.

That was in the early days of Time Machine, I cannot even remember which year, so it may be fixed today.

I have TimeMachine backups sent via Eero WiFi to a Synology NAS, for years. Works even the occasional restores of files. Of course not my only backup in my 3-2-1 regime with various software and hardware redundancies for emergencies.

That’s what I would have thought.

But when I stopped doing it, my data usage dropped back to normal. :woman_shrugging:t2:

Fortunately my monitor has usb-c ports, so I can just attach a drive there. And since connecting to my monitor involves just one easily-accessible cable, it’s not a big deal.

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