Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

giuliomagnifico.medium.com

Post reply on HN
Print view View original

31–40 of 154 posts

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

#31

Post by wtallis »

rvz wrote: post #22
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 do realise if you get this wrong, you can't simply 'replace' the SSD on an Apple Silicon based Mac? You'll likely brick the device if the recovery partition is also wiped in the process. It's back to the Apple Store for you.

For years, Intel Macs have been able to net boot to install the OS onto an empty drive. Did Apple ditch that functionality or move it from the firmware to a recovery partition with the M1 Macs?

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

#33

Post by jabberwcky »

wtallis wrote: post #29
jabberwcky wrote: post #21

Earlier quoted context omitted.

It is still bad advice, zero filling an SSD is not nearly the same as erasing it due to the presence of large (up to 10% or more of the drive) overprovisioning areas present in all devices, ignoring the permanent wear zero-filling the drive also causes, and the fact the controller believes real data remains stored, placing restrictions on its ability to perform internal maintenance

It's fine advice. The wear of writing 1GB of zeros can and should be ignored. It's insignificant. And the drive's spare area is only relevant if you're trying to thoroughly wipe sensitive information from a device before disposing of it. But right now we're just trying to make a device appear functionally empty so that we can re-install an OS without remnants of any previous installation getting in the way. This does…

> But right now we're just trying to make a device appear functionally empty so that we can re-install an OS without remnants of any previous installation getting in the way

The only portable, reliable, robust way to accomplish this is wiping the drive. If the original author had issued a secure erase, they would not have encountered any subsequent difficulties, all of which were due to partially erasing the device.

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

#34

Post by wwweston »

digi59404 wrote: post #25

This is because the author didn't delete the entire volume group. You have to delete the whole volume group, i.e. erase the entire drive and it's partitions to reinstall OSX. This isn't new with the M1 Macs. This has been a thing since they introduced APFS. When they went into disk utility after the cli - Then they could delete everything and kick off the OSX Install. If the APFS Volume Group still exists the install…

Delete the entire drive including the recovery partition?

> There's a specific button for it.

Does the button say "hi, you should pick this unless you're an expert with a really good reason not to?"

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

#35

Post by wtallis »

jabberwcky wrote: post #33
wtallis wrote: post #29

Earlier quoted context omitted.

It's fine advice. The wear of writing 1GB of zeros can and should be ignored. It's insignificant. And the drive's spare area is only relevant if you're trying to thoroughly wipe sensitive information from a device before disposing of it. But right now we're just trying to make a device appear functionally empty so that we can re-install an OS without remnants of any previous installation getting in the way. This does…

> But right now we're just trying to make a device appear functionally empty so that we can re-install an OS without remnants of any previous installation getting in the way The only portable, reliable, robust way to accomplish this is wiping the drive. If the original author had issued a secure erase, they would not have encountered any subsequent difficulties, all of which were due to partially erasing the device.

> The only portable, reliable, robust way to accomplish this

That's setting the bar too high. If we're comfortable with solutions that will work on all mainstream PC platforms including Macs, then it is sufficient to overwrite partition tables with zeros. I have never heard of an OS installer that scans for deleted partitions, and worrying about the possibility of such a thing causing problems is unreasonable.

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

#37

Post by distances »

rvz wrote: post #11

Interesting. These are all the issues I will avoid from early adopters when I eventually get a newer Apple Silicon based Mac computer. I have no time to go through the thorns and landmines over incompatible systems or buggy system software tools from Apple as described by the blog post. Again, I will wait until the software on Apple Silicon is mature and the developer ecosystem catches up to it which by then I'll be…

This seems to be a good strategy with Apple's OS updates too. Most of my colleagues who updated to Big Sur have encountered problems so I'm keeping the strategy of "current minus one", and plan to update to Sur when the next one is out.

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

#38

Post by SXX »

ulzeraj wrote: post #32

Apparently the author erased the APFS volume instead of erasing the physical volume.

You can't wipe actual physical volume on M1 without some command line magic and even then I not sure it's gonna work. Recovery disk utility say it's will wipe it, but it do nothing and Erase Mac option is the same: all it do is erase user data.

I got stuck with almost the same issue even though I'm system administrator and programmer with decade of experience. I can't imagine how all this mess should feel for average Mac or Windows user.

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

#40

Post by giuliomagnifico »

digi59404 wrote: post #25

This is because the author didn't delete the entire volume group. You have to delete the whole volume group, i.e. erase the entire drive and it's partitions to reinstall OSX. This isn't new with the M1 Macs. This has been a thing since they introduced APFS. When they went into disk utility after the cli - Then they could delete everything and kick off the OSX Install. If the APFS Volume Group still exists the install…

I deleted the entire volume if I remember correctly. But even I made a mistake, there should be a warning. I used to HFS FS were there aren’t the volumes so it could have been my error but Apple should put a warning!
Post reply on HN