My iMac won't startup

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Level 1

8 points

My iMac won't startup

I've tried every trick that I could find on Google, but my iMac won't start up. Now that I've waisted half of my workday on trying to figure things out I figured maybe the solution is easier when I ask you guys for help. Now my iMac is from 2017 and it became much slower since I've stored a lot of RAW images on it. Since then I ordered some external hard drives to transfer those RAW images to so it won't be on my iMacs harddrive anymore. But... OFCOURSE as you would expect: I receive the external hard drives today and now my iMac won't start up anymore..

So I really guess it's because my harddrive is so full but through cmnd+R I found out it still has 17GB's left. Does anyone have an idea what the problem might be and maybe if I have to be even more patient and wait several hours for it to start up? Or is it a lost case and do I need to reinstall? I'm trying to make a backup as we speak through iBoysoft.

iMac 27″ 5K, macOS 10.15

Posted on Jul 21, 2020 3:15 AM

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Answer 1

BDAqua

Level 10

250,259 points

Jul 21, 2020 8:50 AM in response to maaike100

Start with this, but 17GB free is not enough these days...

Repair a storage device in Disk Utility on Mac

Disk Utility can fix certain disk problems—for example, multiple apps quit unexpectedly, a file is corrupted, an external device doesn’t work properly, or your computer won’t start up. Disk Utility can’t detect or repair all problems that a disk may have.

If you run First Aid on a disk, Disk Utility checks the partition maps on the disk and performs some additional checks, and then checks each volume. If you run First Aid on a volume, Disk Utility verifies all the contents of that volume only.

In the Disk Utility app on your Mac, choose View > Show All Devices.
Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery, select Disk Utility in the macOS Utilities window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).
In the sidebar, select a disk or volume, then click the First Aid button .
If Disk Utility tells you the disk is about to fail, back up your data and replace the disk—you can’t repair it. Otherwise, continue to the next step.
Click Run, then click Continue.
If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done. You can click Show Details to see more information about the repairs. Otherwise, you may need to do one of the following.

- If Disk Utility reports “overlapped extent allocation” errors, two or more files occupy the same space on your disk, and at least one of them is likely to be corrupted. You need to check each file in the list of affected files. Most of the files in the list have aliases in a DamagedFiles folder at the top level of your disk.
  - If you can replace a file or re-create it, delete it.
  - If it contains information you need, open it and examine its data to make sure it hasn’t been corrupted.
- If Disk Utility can’t repair your disk, or you receive a report that the First Aid process failed, try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, reinstall macOS, then restore your backed-up data.

If your Mac has a Fusion Drive and you see a flashing question mark or alert, see the troubleshooting section of the Apple Support article About Fusion Drive, a storage option for some Mac computers.

If you continue to have problems with your disk or it can’t be repaired, it may be physically damaged and need to be replaced. For information about servicing your Mac, see Find out how to service or repair your Mac.

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Answer 2

maaike100 Author

Level 1

8 points

Jul 23, 2020 12:16 AM in response to BDAqua

Hi, thanks for replying.

Indeed: the 17GB was not enough. So after 36 hours of googling and figuring things out this is my conclusion (spoiler: My imac works again, without resetting anything).. I already tried your explanation aswell so this didn't work for me either. There were several people telling me to indeed try this or that and if it wouldn't work, I'd have to replace stuff or reset it or whatever.. Resulting in me losing some of the data that I didn't backup. So if it wasn't for me being a very stubborn person, I would've listened.

For others having the same problem, this was the problem & how I solved it:

My iMac wouldn't start up anymore because there wasn't enough space to start it up. I tried all the possible 'tricks in the book' that I could find and finally I used the Target Disk Mode trick. This is the one that saved my iMac. I have an iMac and a Macbook, which is what you need for this one (2 mac's or 2 macbooks or whatever). Then I had a thunderbolt cable to connect the iMac that wasn't booting to my Macbook. First I had to update my macbook because for this both of your devices have to have at least High Sierra on it (my Macbook was still on El Capitan). After the update I connected both of the devices with the thunderbolt cable and started up my iMac while holding T until the thunderbolt appeared on my screen. At this point my iMac works as a External hard drive on my Macbook. Thus; I could go through my files of my iMac on my Macbook. Ofcourse at this point I made some backups of files and then I chose to delete some big files (hard delete it so it surpasses the trashcan: cmnd option delete). I was too excited and restarted my iMac right away. Didn't work yet. So I made some more backups and in the mean time I could see in Disk Utility that the disk was now less full. Time to try again: This time it worked! My iMac started up normally again and nothing was lost.

Hope this helps someone in the same situation as me!

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My iMac won't startup

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