Don’t format a drive of M1 Macs from recovery mode

#1

Post by giuliomagnifico » Thu, Feb 18, 2021, 8:09 AM UTC

Don’t format a drive of M1 Macs from recovery mode
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Re: Don’t format a drive of M1 Macs from recovery mode

#2

Post by simonh » Thu, Feb 18, 2021, 8:38 AM UTC

The one area with these M1 Macs that seems barely even half cooked is how they treat their disks. Does anyone know if this due to hardware limitations in the M1 architecture, or are the restrictions in the firmware level? I'm wondering if this is even fixable by Apple in later updates.

Re: Don’t format a drive of M1 Macs from recovery mode

#3

Post by jonwest » Thu, Feb 18, 2021, 8:43 AM UTC

Same, or similar behaviors with the 2020 Intel MBP. I ended up having to format the drive as an exFAT drive and then reformat again as APFS to get it to reinstall it was a real pain in the ass.

Re: Don’t format a drive of M1 Macs from recovery mode

#4

Post by giuliomagnifico » Thu, Feb 18, 2021, 8:44 AM UTC

simonh wrote: post #2

The one area with these M1 Macs that seems barely even half cooked is how they treat their disks. Does anyone know if this due to hardware limitations in the M1 architecture, or are the restrictions in the firmware level? I'm wondering if this is even fixable by Apple in later updates.

I suspect is due to a security choice from Apple, a firmware upgrade should fix it, or at least put a warning or doesn’t allow you to erase the whole SSD if you can’t install macOS after.

Re: Don’t format a drive of M1 Macs from recovery mode

#5

Post by devit » Thu, Feb 18, 2021, 8:51 AM UTC

Why not just do the usual dd if=/dev/zero of= bs=1M count=1024 instead of using those weird proprietary tools?

Re: Don’t format a drive of M1 Macs from recovery mode

#6

Post by sillysaurusx » Thu, Feb 18, 2021, 8:52 AM UTC

devit wrote: post #5

Why not just do the usual dd if=/dev/zero of= bs=1M count=1024 instead of using those weird proprietary tools?

You'd likely brick your mac if you don't do it the anointed way.

Re: Don’t format a drive of M1 Macs from recovery mode

#7

Post by giuliomagnifico » Thu, Feb 18, 2021, 8:53 AM UTC

jonwest wrote: post #3

Same, or similar behaviors with the 2020 Intel MBP. I ended up having to format the drive as an exFAT drive and then reformat again as APFS to get it to reinstall it was a real pain in the ass.

But at least with an intel Mac you can boot in target mode using cmd - t and then clone/mount/erase/whatever the disk from another Mac!

Instead with ARM you can’t mount the disk as an external drive. That’s why this mess started!

Re: Don’t format a drive of M1 Macs from recovery mode

#8

Post by jabberwcky » Thu, Feb 18, 2021, 9:02 AM UTC

devit wrote: post #5

Why not just do the usual dd if=/dev/zero of= bs=1M count=1024 instead of using those weird proprietary tools?

This option is horrendously inefficient on most modern drives. For many SSDs, issuing a secure erase request is an almost instantaneous process as it only requires the drive to generate a replacement encryption key, and need not even entail bulk writing or erasing physical flash pages

Re: Don’t format a drive of M1 Macs from recovery mode

#9

Post by my123 » Thu, Feb 18, 2021, 9:02 AM UTC

sillysaurusx wrote: post #6

devit wrote: post #5

Why not just do the usual dd if=/dev/zero of= bs=1M count=1024 instead of using those weird proprietary tools?

You'd likely brick your mac if you don't do it the anointed way.

As long as you don't shoot yourself in the foot by touching other NVMe namespaces (and even that should be recoverable) and the SPI flash onboard, things can be restorable through DFU.

Re: Don’t format a drive of M1 Macs from recovery mode

#10

Post by fouc » Thu, Feb 18, 2021, 9:03 AM UTC

>Uff…what a paintful process!

If an issue takes less than 5 different attempts to resolve and under 1-2 hours to fix, that can't really be called painful, merely annoying. Especially when it's only a one-time problem.