Tuesday, November 12, 2024

terminal – corrupted disk1s2, deleted partition entirely, now unable to replace GUID

A brief disclaimer: I have very little experience with computers at this level, and this is my first time posting on forums, please forgive me for any imprecise, incorrect, or unclear terminology, as well as for any breach of conduct in the structure of this post

In trying to set up dual-booted linux on my c. 2014 era macbook, I corrupted my install of macOs Monterey to an unbootable state. Booting to internet recovery mode, I attempted to use the first aid tool to repair the disk, which identified that the disk was not bootable, but did not repair it. After running gpt -r show disk1 in the terminal, I saw that disk1s2 had changed to FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF.
photo of laptop screen containing output for gpt -r show disk1

Using that identifier as a keyphrase, I found [this ask different forum post] and followed the steps. However, I did not receive an output from dd if=/dev/disk0s2 count=3 | vis -c that seemed to be anything similar to the provided sample strings for either a standard or a CoreStorage partition.

Regardless, I continued following the steps, unmounting my drive and removing the 3rd, 4th and 2nd partitions. When attempting to re-add the partitions, I first used the type and index number provided for the normal OSX partition, which returned an error of not enough space. I proceeded to try the index numbers for the other two partition tpyes listed, both of which returned the same error.

I came to realize that depending on the specific partition and MacOS version, that the index types and numbers vary largely, and I assume that I would be able to get the exact information I needed from forum posts, however my own attempts to find this information from other sources were unsuccessful.

It was at this point I allowed an acquaintance who had experience in laptop repair to take over. They proceeded to restart the macbook and tried internet recovery, to the same success that I had found when attempting the same approach.

This detour not only cleared the terminal and all the logs I had not had the presence to properly document, but upon re-running gpt -r show disk1 partitions 2 and 4 were both gone.
output of gpt -r show disk1 after reboot

Using this forum post I attempted to get the gdisk command to fix the GUID Partition Table. The script provided initialized, but no data was transferred, despite a valid internet connection. I attempted to download the tool without using the script using the list of commands provided later on, to a similar lack of success.
gdisk install fail

Is it still possible to get MacOS to a bootable state without losing any of the files I have saved? (assuming that re-starting mid-repartitioning didn’t wipe everything)

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