Using an M1 Mac: some basic principles

M1 series Macs are different in almost every respect from the Intel Macs which have preceded them. Most days, someone emails me asking whether it’s possible to clone macOS from their internal SSD and use it for recovery, or any of thousands of variations. This article explains the basics of using an M1 Mac, including how to provide for disaster recovery, so that you can decide how best to set yours up. Although M1 Macs have some unique restrictions, in many ways they’re among the most flexible of Apple’s recent models. Learning how not to come into conflict with their restrictions, and how to get the best of their flexibility, is essential if you’re going to get the most out of your M1 Mac.

The most common basic configuration for an M1 Mac is that it boots from the single version of the latest macOS on its internal SSD, with the whole of its Data volume on that disk, and File Vault enabled. It backs up using Time Machine to APFS, to an external SSD which is connected to one of its USB-C ports, with those backups encrypted.

Disaster recovery

There are four scenarios to prepare for in terms of disaster recovery.

The simplest is loss or damage to data on the Data volume, on the internal SSD. The response is to open Time Machine and restore the files from there. If the entire Data volume becomes damaged, it may be necessary to restore the whole volume from the backup, which is simple to perform in Recovery, after you have run First Aid on the volume using Disk Utility there.

Next up is damage to the System. This is prevented by the fact that M1 Macs, like Intel models, booting from Big Sur or Monterey do so not from a mounted volume, but from a signed and sealed snapshot. In the Secure Boot process, the top-level Seal is checked, and if that no longer matches that set by Apple for that version of macOS, that Mac should be automatically booted into Recovery for macOS to be re-installed. Because snapshots are read-only and can’t be changed in any way, the chances of a corrupt System snapshot occurring are very low.

However, Recovery doesn’t provide an option for you to try cloning back a copy of the System volume, which your Mac couldn’t boot from anyway, as it requires a signed and sealed snapshot, which can’t always be created on the internal SSD by third-party software. The only reliable and sound approach is to use Recovery to re-install macOS.

The macOS installer may be able to reunite your existing, undamaged Data volume with its new System volume, but in most cases you should expect to migrate your data back from a Time Machine backup or a copy or clone of the Data volume, on an external disk.

Beyond that is soft damage to the whole of the internal SSD. What the user can’t normally see is that this isn’t just the container (partition) for macOS, but includes two hidden containers too: the Pre-Boot container is used for what is effectively the firmware, which runs during the early stages of booting, and for secure storage of the various keys and other data to support the Secure Boot process. The other container holds a Recovery system, although in Monterey that copy isn’t the one normally used for Recovery; it is the primary Recovery system for Big Sur, though.

If the Pre-Boot container is damaged, the Mac is unable to boot, even though it may be connected to a bootable external disk, as the only Pre-Boot it can use in the early part of the boot process is that located on the internal SSD. In that case, the only way forward is to put the Mac into DFU mode, which isn’t dependent on an intact internal SSD, connect it to another Mac running Apple Configurator 2, and from there restore its internal SSD using an IPSW image file downloaded from Apple, a technique detailed in Configurator’s Help book. This puts the Mac back to factory condition, and it then has to be booted, personalised and set up just as it was when it was first delivered.

Many users think this a severe limitation, but M1 Macs are, to the best of my knowledge, the only Macs that Apple has made which can be taken right back and restored by the user in this way. If the firmware in an Intel Mac is corrupted, it can be very difficult to get that Mac working again, and failed firmware updates are a well-known cause of ‘bricking’ of Macs with the T2 chip, which also needs the ministrations of Configurator to fix them. What’s truly remarkable, though, is that you can use this technique to restore older versions of the ‘firmware’ and macOS on an M1 Mac, something not possible on an Intel model.

If you don’t have access to a second Mac, all Apple stores and authorised service providers should be able to restore an M1 Mac while you wait. It normally takes less than 15 minutes.

The ultimate disaster for the internal SSD is hard failure. Because it’s soldered to the logic board, the only remedy is a replacement logic board, which is performed under warranty and AppleCare by an authorised service provider. Again, this often meets with howls of derision, but if you want the performance attained by the internal SSD, there aren’t many options. It also makes M1 series Macs a tougher proposition for thieves. You’d have exactly the same problem if the failure had occurred in the M1 chip itself, or in any other key component on the logic board, but I’ve never heard of complaints about that.

Modern high-quality SSDs have extremely low failure rates. If you’re concerned at the risk of this occurring when you’re travelling, I think in many cases you’re more likely to end up in Intensive Care than your Mac’s SSD suffers complete failure.


Contrary to some opinion, M1 Macs are straightforward to boot from an external SSD, although you must never confuse that process with booting an Intel Mac from an external disk. In the latter, the whole of the boot process can run from the external SSD. M1 Macs invariably start their boot process from their internal SSD, and only then transfer to the external boot system.

Currently, it may be possible to clone a System and Data volume to an external SSD and make it bootable. However, that isn’t recommended, and the best and most reliable way to create an external bootable disk is using a macOS full installer app, or in Recovery. If that is to install an older version of macOS, it may need to be installed from a bootable install disk, as recent versions of macOS usually block older versions.

Once you’ve made a bootable external disk, and its ownership is recognised by macOS so that Mac can start up from it, you can use that disk with other M1 Macs. You may be able to boot Intel Macs from it too, but there are some things which may be installed on it which they don’t understand, like Rosetta 2, neither will they grok the volume ownership issues inherent in M1 Macs.

Unlike Intel Macs with T2 chips, you don’t have to change an M1 Mac’s security settings for it to boot happily from an external disk. What’s more, you can set that disk up to boot at a reduced security level so it can load third-party kernel extensions, and do other things not permitted in full security.

You can also repartition your M1 Mac’s internal SSD to provide additional containers, and install multiple bootable copies of macOS on that internal storage. However, when you do this, remember that your Mac is reliant on that SSD to enable it to boot. Make a mess of it, and you could well be restoring it in DFU mode. Some changes don’t appear well-tolerated: creating an HFS+ volume (partition) on the internal SSD doesn’t go down well, for example.

You can also install multiple versions of macOS in a single container if you wish. Remember that, in Monterey, they will each have their own Recovery volume, and consider whether it would be cleaner and clearer to install those into separate containers, for instance.

M1 Macs have a great many options as to how you can configure and boot them, but always remain within their basic rules, most important of which is that their boot process always starts from the internal SSD. Follow those rules and play safe, and you should avoid the frustrations which experimental configurations could bring.