iMac Hard Drive Issues

z3phyreon

macrumors newbie
Original poster
Dec 15, 2018
1
0
Hey there.

I've got a late 2015 27in Mojave (should be latest 10.X version) iMac whose hard drive may have died so I'm trying to salvage what I can. No currently valid warranty, so here we go. Last week I woke it from sleep on 12/7 and all actions were taking an unnaturally long time to process: opening a small folder took 3+minutes, for example. **Note: I do have an external 2TB drive for Time Machine purposes -- I set it up back in July-ish, and it was set to run daily, which it did up until 12/6-7 when it started running seemingly every 40 minutes (this was seen in the Time Machine date logs). The delay in processing time rendered the machine virtually inoperable. I shut down and booted into Recovery mode to run through Disk Utility/First Aid, but the disk checks came back fine. Tried to boot/restart normally a few times, but the performance/processing issues persisted. I had a Windows 10 partition set, so I tried logging into that to see if it was running any differently, but I couldn't even get through the boot screens.

Back to the OS X Recovery mode, I said 'Screw it, I'll just restore from my Time Machine backup.' That took four days to complete, then when it did the system hung at what looked like the final restore step with the Apple logo and the progress bar underneath. It hung here for 6+ hours until I gave up, shut the system down and went back to the Recovery mode to try the Reinstall OS X option, which initially failed with a 'Cannot connect to recovery server' error. At this point, I said screw it and went back to the Disk Utility and tried to erase and reformat the drives in an effort to start fresh.

After erasing and reformatting what target disks I could (originally as APFS, then as Extended Journaled), I was able to get the Reinstall OS X option to fire, but the installation failed out and hung, again, on what seemed like the final step and failed to complete. In short, both the Recovery Reinstall OS X -and- command-alt-r Internet Recovery run course but either fails or hangs and never completes. Throughout the terminal/diskutil interactions, I've noticed that there are quite a few extraneous disks listing with extremely small file sizes that I can't seem to get rid of, in particular /disk6 through /disk22. Beyond that (I might be getting too tunnel-visioned on this at this point, been trying to get this resolved for over a week), it looks like there are duplicate images/fragments of the main drive. Preboot = the name of the latest disk erase/reformat. I'm thinking that the installations/repairs/recoveries are failing because the drive is so fragmented. Below is the diskutil output.

-bash-3.2# diskutil list
/dev/disk0 (internal):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme 24.0 GB disk0
1: EFI EFI 314.6 MB disk0s1
2: Apple_CoreStorage Preboot 23.6 GB disk0s2
3: Apple_Boot Boot OS X 134.2 MB disk0s3

/dev/disk1 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *2.0 TB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_HFS Time Machine 2.0 TB disk1s2

/dev/disk2 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +2.1 GB disk2
1: Apple_HFS OS X Base System 2.0 GB disk2s1

/dev/disk3 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +5.2 MB disk3

/dev/disk4 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk4
1: EFI EFI 209.7 MB disk4s1
2: Apple_CoreStorage Preboot 999.7 GB disk4s2
3: Apple_Boot Boot OS X 134.2 MB disk4s3

/dev/disk5 (internal, virtual):
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS Preboot +1.0 TB disk5
Logical Volume on disk4s2, disk0s2
C4BA7933-7DE1-43FA-A73B-99680D89E924
Unencrypted Fusion Drive

/dev/disk6 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk6

/dev/disk7 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk7

/dev/disk8 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk8

/dev/disk9 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +2.1 MB disk9

/dev/disk10 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk10

/dev/disk11 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk11

/dev/disk12 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +12.6 MB disk12

/dev/disk13 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +4.2 MB disk13

/dev/disk14 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +1.0 MB disk14

/dev/disk15 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +2.1 MB disk15

/dev/disk16 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk16

/dev/disk17 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk17

/dev/disk18 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +1.0 MB disk18

/dev/disk19 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +6.3 MB disk19

/dev/disk20 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +6.3 MB disk20

/dev/disk21 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +524.3 KB disk21

/dev/disk22 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: untitled +2.1 MB disk22

The end goal of what I'm trying to is simply restore the drive to a single disk and start from scratch but I cannot manage to find the correct commands/syntax to delete the /disk6-22 items, nor how to erase/clean/merge /disk0-5. Every time I try to erase/format down into a single disk, it seems like matters are made worse. I understand that disk 2 is the recovery drive, so I'm not concerned with that.

Any help or advice is much appreciated.

Thank you.
 

Lunder89

macrumors 6502
Oct 16, 2014
393
128
Denmark
You have an iMac with a fusion drive, and I seem to recall reading a lot about them failing lately. So I guess your harddrive is slowly dying.

But about the disks you can identify (6-22) they are connected disk images. Could be from the USB thumb drive or just the installer that found a lot of disk images around, or creates them for recovery purposes. I am not really sure. Could be one files that is just buggy and is messing with Disk Utility and you. But they are NOT drive partitions.

I would consider getting a new harddrive in the computer. Especially the problems you describe when the Mac is running.
 

Fishrrman

macrumors P6
Feb 20, 2009
17,170
5,528
OP:

Long posts like yours above are usually all-but-indecipherable when trying to help.

My suggestion:
Buy a smallish-sized EXTERNAL USB3 SSD drive.
250gb will "do the job" (but you could get one larger if you wished).
I'd suggest a Samsung t5 or Sandisk Extreme.

Once you have it:
Have the Mac powered off.
Connect the external USB3 SSD.
Then, boot to internet recovery (command-option-R).
Open Disk Utility and erase the SSD to "Mac OS extended with journaling enabled".

Once erased, open the OS installer.
"Aim it" at the external SSD.
Install a fresh copy of the OS onto the external drive.
When done, set it up with a basic account.

WHY DO THIS?
Now you have a way to "get booted to the finder" without using the internal drive.
The idea is to get "fully booted", and then you can work on getting the internal drive back to where it should be.

Realize that it may not be possible to do so, IF one of the internal drives has failed.
It could be the SSD portion of the fusion drive, but might be the HDD portion.

IF you had chosen to back up using either CarbonCopyCloner or SuperDuper, you would already have a "fully bootable backup".
Getting running again with a cloned backup is literally "child's play".