Unable to format disk mac
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Math.drstr
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Math.drstr Posted messages 10 Status Member -
Math.drstr Posted messages 10 Status Member -
Hello,
After 3 days of relentless effort, I turn with hope to this forum in the hope that someone more skilled than I has the solution.
I have a 27" iMac from 2011 (running High Sierra and Windows 10 in dual boot) that I had to reset (lost admin password) with a new 1TB Samsung 860 Evo SSD that’s only two months old. After several tweaks of all kinds to solve various problems, here is the current state of affairs:
No operating system installed on the machine, recovery startup impossible (not even via internet, which is quite strange since I receive a network error while everything is fine on that side), and when I use a pre-created TechTool ToGo drive, I can't format the disk: the "creating partition table" step goes on indefinitely. Using the terminal yields the same result (stuck at 50%). Similarly, when I attempt to partition the disk, the utility crashes and closes. One last anomaly, and not the least: among the two volumes displayed in the disk utility, one is an APFS (on which macOS can be installed, at least that's good) of 500GB and the other is a non-mountable volume of about -120MB (how is that even possible, I don't know).
So we see two issues: one, it's impossible to perform actions on the disk, and two, 500GB is unaccounted for, in addition to a disk with negative capacity. After using the disk utility's First Aid and testing the partition map with TechTool, it seems the problem arises from the latter (both indicate an error on it) but it's impossible to fix the issue (attempts with TechTool and various other tools).
I hope this doesn't mean the disk is dead (at €150 that would really suck, especially since it’s probably not covered by warranty). I plan to remove the disk from the Mac and connect it externally to my Windows PC to see if I can try something on that side with other tools or commands.
Thank you in advance for your help.
After 3 days of relentless effort, I turn with hope to this forum in the hope that someone more skilled than I has the solution.
I have a 27" iMac from 2011 (running High Sierra and Windows 10 in dual boot) that I had to reset (lost admin password) with a new 1TB Samsung 860 Evo SSD that’s only two months old. After several tweaks of all kinds to solve various problems, here is the current state of affairs:
No operating system installed on the machine, recovery startup impossible (not even via internet, which is quite strange since I receive a network error while everything is fine on that side), and when I use a pre-created TechTool ToGo drive, I can't format the disk: the "creating partition table" step goes on indefinitely. Using the terminal yields the same result (stuck at 50%). Similarly, when I attempt to partition the disk, the utility crashes and closes. One last anomaly, and not the least: among the two volumes displayed in the disk utility, one is an APFS (on which macOS can be installed, at least that's good) of 500GB and the other is a non-mountable volume of about -120MB (how is that even possible, I don't know).
So we see two issues: one, it's impossible to perform actions on the disk, and two, 500GB is unaccounted for, in addition to a disk with negative capacity. After using the disk utility's First Aid and testing the partition map with TechTool, it seems the problem arises from the latter (both indicate an error on it) but it's impossible to fix the issue (attempts with TechTool and various other tools).
I hope this doesn't mean the disk is dead (at €150 that would really suck, especially since it’s probably not covered by warranty). I plan to remove the disk from the Mac and connect it externally to my Windows PC to see if I can try something on that side with other tools or commands.
Thank you in advance for your help.
2 answers
Hello,
Quick reply...
I don't think I understood everything, for example:
If you're saying that you replaced the internal hard drive with an SSD, or that you added an SSD to the Mac (as I did on my mid-2011 iMac), in either case, you must have installed the system on this SSD, and you should have had a valid boot drive with macOS installed on it, or you could have booted from a recovery partition over the internet (holding down the Alt + Cmd + R keys at startup).
In any case, the old hard drive should be functional and may still contain a valid system, but with a forgotten password.
If this drive is no longer in the Mac, you can still put it in an enclosure and boot from this drive in single user mode and reset the password using this method:
https://www.commentcamarche.net/faq/44961-reinitialiser-un-mot-de-passe-utilisateur-sous-mac-os-x-10-6-et-versions-anterieures-sans-disque-d-installation#methode-alternative
The fact that I see a 120 MB partition makes me think of an EFI type partition. This partition is usually hidden. Only a few utilities can display it.
Otherwise, given the issues encountered, I feel like the system was installed on a physical medium with the wrong scheme. MBR instead of GUID, for example.
In Disk Utility, you need to select the physical part of the drive before starting an erase, and then choose the GUID scheme for formatting.
Sometimes the physical part isn't displayed in Disk Utility; only the volumes are shown... in that case, you need to go to the menu bar and select to show All Devices...
I have to step out now, I will be back later in the day...
@++
Quick reply...
I don't think I understood everything, for example:
I had to reset (lost the administrator password) with a new 1TB Samsung 860 Evo SSD that’s two months old.
If you're saying that you replaced the internal hard drive with an SSD, or that you added an SSD to the Mac (as I did on my mid-2011 iMac), in either case, you must have installed the system on this SSD, and you should have had a valid boot drive with macOS installed on it, or you could have booted from a recovery partition over the internet (holding down the Alt + Cmd + R keys at startup).
In any case, the old hard drive should be functional and may still contain a valid system, but with a forgotten password.
If this drive is no longer in the Mac, you can still put it in an enclosure and boot from this drive in single user mode and reset the password using this method:
https://www.commentcamarche.net/faq/44961-reinitialiser-un-mot-de-passe-utilisateur-sous-mac-os-x-10-6-et-versions-anterieures-sans-disque-d-installation#methode-alternative
The fact that I see a 120 MB partition makes me think of an EFI type partition. This partition is usually hidden. Only a few utilities can display it.
Otherwise, given the issues encountered, I feel like the system was installed on a physical medium with the wrong scheme. MBR instead of GUID, for example.
In Disk Utility, you need to select the physical part of the drive before starting an erase, and then choose the GUID scheme for formatting.
Sometimes the physical part isn't displayed in Disk Utility; only the volumes are shown... in that case, you need to go to the menu bar and select to show All Devices...
I have to step out now, I will be back later in the day...
@++
Hello,
I finally decided to take the drive out of the Mac and connect it externally with an adapter to my PC where I have some more powerful tools than what's available on Mac. With that, I was finally able to recreate a clean partition table and reformat the drive. Unfortunately, since then I've been unable to reinstall Windows in dual boot. It’s a small consolation considering macOS is working fine.
I think I'll close the topic now, and for anyone who might have a similar issue: the drive is not dead, you just need a powerful enough utility to force the formatting of the drive. I should mention that I originally switched to an SSD due to a similar issue (the original hard drive's partition table was dead) and with the same tool, I managed to recover it.
I finally decided to take the drive out of the Mac and connect it externally with an adapter to my PC where I have some more powerful tools than what's available on Mac. With that, I was finally able to recreate a clean partition table and reformat the drive. Unfortunately, since then I've been unable to reinstall Windows in dual boot. It’s a small consolation considering macOS is working fine.
I think I'll close the topic now, and for anyone who might have a similar issue: the drive is not dead, you just need a powerful enough utility to force the formatting of the drive. I should mention that I originally switched to an SSD due to a similar issue (the original hard drive's partition table was dead) and with the same tool, I managed to recover it.