Disk full/computer failing to complete startup

Question

Disk full/computer failing to complete startup

Hi

I have an old iMac running 10.15.7 (with a 1 tb fusion drive).

I downloaded some photographs from an iPad into the photos app on the iMac, all worked/was working fine and I turned the computer off (using the shutdown in the menu etc). However, when I now go to turn it on I get the “chime” the screen with the apple and the progress bar (which will slowly load to 100%) but nothing beyond that/no login screen.

I managed to start up in recovery mode (command + r) and I think the cause of the issue is that the disk is full. Disk utility in recovery mode shows the following

MacintoshHD 11.33 GB used 17.07GB free

MacintoshHD - data 991.99 GB used and 17.07 GB free

MacOS Base System: 1.35 GB used and 658.7 MB free.

Clearly I need to delete some of the photographs I downloaded (and maybe some more file as well). However how do I do that please/what should I be doing in disk utility in recovery mode so that I can get to the login screen/and login so I can delete the files?

I do have 3 Time Machine backups, but I would like to avoid erasing the drive if at all possible - not least as I think that would mean the latest OS would be downloaded (where I recall there were problems with fusion drives) and I am quite happy using Catalina.

Thank you.

iMac (2017 – 2020)

Posted on Apr 29, 2024 8:22 AM

Reply

Answer 1

Apr 29, 2024 10:35 AM in response to Think_differently123

With Internet Recovery depends on some some key combinations, which macOS options are available for a particular Mac. It might take 20-30- minutes to boot into the macOS installer (and the the actual install 30-60 minutes) so be patient and hope Apple's servers behave and your network connection is fast enough and robust. (I always make an offline bootable USB macOS installer so I have never really needed to do Internet Recovery, but I have glanced it a few times, just in case).

Use macOS Recovery on an Intel-based Mac - Apple Support

Reply

Answer 2

BDAqua

Level 10

239,897 points

May 5, 2024 4:15 PM in response to Think_differently123

(0):I've been hooting my 2019 imac from external SSDs since new.

That is the point where user things start loading. Are you running any VPN, Anti-Virus, or Cleaning apps?

We need to see what all is running, a report from this will not display any personal info...

Using EtreCheck - Apple Community

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Thanks for Old Toad’s etrecheck instructions…

Slow iMac 2017 - Apple Community

Use the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Earlier versions of etrecheck...

https://macdownload.informer.com/etrecheck/versions/

Two. Likely you Installed to half the drive, from Catalina up Apple split theboot drive into 2 Macintosh HD & Macintosh HD - Data.

In Disk Utility>View, select Show all Devices, highlight the top left entry of the drive in question

Reply

Answer 3

Apr 29, 2024 9:45 AM in response to Think_differently123

And one other thing i have read is this View APFS snapshots in Disk Utility on Mac – Apple Support (UK)

I can see in disk utility 5 Time Machine snapshots. Would deleting those cause any problem please?

Reply

Answer 4

May 5, 2024 2:58 PM in response to HWTech

Thanks HWTech.

Disk utility says everything is fine.

Is there any downside simply continuing to run everything from an external SSD? I assume I should create a boot disk from a small thumb drive with just Ventura on it?

Two odd things that I have noticed:

Restarting the computer is slow. It loads about 50% of the progress bar quickly but then the last part is slow to load. However I must confess that once it gets going it is quicker (I assume that is because everything is on an SSD rather than the Fusion Drive) than it was before.
According to the computer I am now using just over 1TB of a 2 TB SSD. I purchased a second 2 TB SSD to ensure I had a second backup (in addition to a backup from an old time capsule) just in case. However after the first backup (I formatted the drive before doing anything) the 2 TB SSD said there was only some 250 GB left. Thus there seems to be a phantom 750GB?

Reply

Answer 5

Apr 29, 2024 9:23 AM in response to Think_differently123

Can you boot in safe mode and then move some large files to an external disk?

Or boot from an external disk and do some housekeeping on the internal disk?

Or use the Terminal in Recovery mode to move (or trash unimportant) large files elsewhere (that might be risky if you are not comfortable using the common line)?

Reply

Answer 6

Apr 29, 2024 9:38 AM in response to Matti Haveri

Thanks Matti.

I have tried booting in safe mode (shift key?). However I get the chime, black screen with the apple logo and progress bar, the progress bar goes quickly to about 60% but then slows right down and nothing seems to come up.

I have some external SSDs but none have an OS on. Is there any way I can put an OS on one of those? I assume not (I do have a mac with Apple silicon but I don’t think that works to let me boot the Intel iMac in target mode)?

I have also run disk utility in recovery mode on the 3 volumes aBose and it says everything is OK.

I am afraid Terminal is beyond me.

Reply

Answer 7

Apr 29, 2024 9:56 AM in response to Think_differently123

Trying target disk mode or deleting snapshots are good ideas (AFAIK macOS should automatically delete snapshots when space is getting low, though?). One option might be to use (Internet) Recovery mode to install macOS on an external volume and then boot to to access the internal volume.

But if all else fails, it is a good thing that you have backups.

Reply

Answer 8

Apr 29, 2024 10:13 AM in response to Matti Haveri

How do I use internet recovery mode to install Catalina onto an external SSD please? Is it simply a case of plugging the external SSD into the iMac and starting internet recovery mode and it will then download Catalina to the external SSD?

Reply

Answer 9

Apr 30, 2024 7:46 AM in response to Matti Haveri

Just to say (in case anyone else encounters the same problem) that I was able to download Ventura to the external SSD through internet recovery mode (Catalina and High Sierra would not work), boot from that and then migration assistant worked to transfer everything from the internal disk to the SSD and so I will run Ventura off the SSD (it seems quick enough for me).

Reply

Answer 10

Apr 30, 2024 9:21 AM in response to Matti Haveri

I didn’t have to as I just moved everything across to the larger ssd with migration assistant and booted from that.

I suppose what I should really do is now wipe the internal drive (which I think is fine) and install Ventura on that in case the external drive fails?

Reply

Answer 11

HWTech

Level 9

56,186 points

May 2, 2024 11:15 AM in response to Think_differently123

Maybe try running Disk Utility First Aid on the hidden Container on the internal drive. Safe Mode was also a good idea, but since it did not get as far as a normal boot that tells me that the internal hard drive portion of the Fusion Drive may be failing. 17GB should have been enough to boot the Mac in Safe Mode.

You can try running DriveDx (free trial period) to check the health of the internal drives and posting the complete text reports here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar.

Reply

Answer 12

May 5, 2024 10:52 PM in response to Think_differently123

> Is there any downside simply continuing to run everything from an external SSD? I assume I should create a boot disk from a small thumb drive with just Ventura on it?

Not much except you must remember to keep the drive connected and powered when using the Mac. But there are drives that do not need external power so this is a minor issue. USB thumb drives do work but they are usually slow and not so reliable as proper SSDs.

> Restarting the computer is slow. It loads about 50% of the progress bar quickly but then the last part is slow to load.

I have an external test 1 TB SATA SSD with 530 MB/s. It has about 6-8 bootable test volumes including one Carbon Copy Cloner backup (the other CCC backup on its own SSD):

At one point booting from it became slower than before -- halfway during the boot it almost stalled, then finished and was as snappy as always. It had a couple of older Sonoma versions, Mojave and quite a few CCC snapshots on its backup volume. At one point I updated all those Sonoma volumes to the latest and also deleted CCC snapshots to make room for a movie project (there was at 50-100 GB free space before that so lack of space was not an issue). I do not know if related to either of those changes, the boot then was again snappy. Maybe the slowness was related to some hidden boot partition that was out-of-sync with the other volumes or maybe inspecting those many snapshots took extra time etc? Go figure.

Reply

Answer 13

Apr 30, 2024 7:56 AM in response to Think_differently123

Glad you got it working. Did you succeed in making more space for the internal volume, and can you then boot also from it? Is the internal disk still OK?

Reply