Use target mode to repair HD?

[juicer52]

I have a mid 2011 27" iMac i7 with a possible failed HD.
I also have a mid 2009 working 27" iMac i5.
After playing around with an external Linux HD, somehow now when I turn the Mac on, it goes to a grub> command page.
The Mac runs flawlessly using a Live Linux Mint CD. (bypassing the internal HD?)
Using option key at startup, I see the Mac Hd boot SSD drive and Mac HD storage drive as well as now an EFI boot.. No recovery partition is visible.
No matter what option I choose or even Command+R it eventually goes to a gray screen.
Is there a way using target Mode to check/repair the 2011 HD using the 2009 as host?
What other options are available to get the 2011 back and running?

 

[vansmith]

Have you tried using internet recovery by holding down Command-Option-R?

To answer your question, I'm not sure if you can run a disk check from Target Disk Mode. I suppose the easiest way to know is to put the 2011 in TDM and see if the disk shows up in Disk Utility on the 2009 Mac.

(It looks like you tried to install Linux. The "grub>" prompt is the Linux boot loader Grub's command line interface. Just FYI.)

 

[juicer52]

In addition to Command+R, I did try the Cmd+Option+R Internet Recovery. Completes the progress bar after a short while, then goes to PANIC gray screen. Doesn't open the Utilities program. Not sure if this is an issue with currently installed High Sierra being an older OS, no longer in the Apple Store, and only available for download and installation as an image for bootable USB??
The Firewire cable for Target Mode probing is on order. When it arrives, I will be able to see what if anything remains on the Macintosh HD boot SSD or if it is wiped or otherwise farked.
I'm almost certain I did not try to install Linux but did run it from the Linux Mint Live CD and did try to run it from an external drive as well. The Live CD runs perfectly on the 2011 but the External Drive never booted. I think that trying to boot (not install) from the external Linux HD is when grub> first appeared.
I figured out that from boot holding Option, by holding Control as I select the boot option, the next time I try to start the Mac without Option, it automatically tries to boot from that last selection. At least I am no longer looking at the grub>.
I read that (if I ever get this Mac running again), I can delete the Ubuntu grub> entry.
The Mac runs perfectly on the Linux Live CD, albeit understandably slow, which leads me to believe the hardware is OK and the fault that leads to PANIC is in the software.
I'm no expert and am frustrated fumbling around in the dark.
I appreciate the suggestions and directions.

 

[ferrarr]

Yes, you can use Disk Utility to check the newer iMacs HDD while using Target Disk Mode. The iMac hd (if working) will show up as an external drive.

Also, an NVRAM reset, should set the startup disk to its' default (internal?) drive.

 

[juicer52]

Yes, you can use Disk Utility to check the newer iMacs HDD while using Target Disk Mode. The iMac hd (if working) will show up as an external drive.

Also, an NVRAM reset, should set the startup disk to its' default (internal?) drive.

I did try NVRAM reset but it didn't work as expected. Only holding control while choosing the boot device after Start+Option returned the boot sequence to the one just selected. In so doing, I selected he Macintosh HD instead of EFI so grub> was gone at reboot. Still goes to gray screen after short delay on progress bar.
D on startup run in extended mode shows no problems. If I am reading the screen properly Command+S indicates boot drive is "not readable". However, /sbin/fsck -fy indicates drive is fine (though "f is disabled").
Curious why the Mac will boot from the Linux Mint live CD but will not boot from an external HD with High Sierra installed which shows as an option on Start+Option.

 

[ferrarr]

How bout safe mode?

Start up your Mac in safe mode - Apple Support

To help determine whether an issue is caused by software that loads as your Mac starts up, you can start up your Mac in safe mode.

support.apple.com

 

[juicer52]

How bout safe mode?

Start up your Mac in safe mode - Apple Support

To help determine whether an issue is caused by software that loads as your Mac starts up, you can start up your Mac in safe mode.

support.apple.com

Nope, no boot in Safe Mode. Start+Shift - Logo appears then progress bar nearly to end then gray screen.

 

[ferrarr]

Nope, no boot in Safe Mode. Start+Shift - Logo appears then progress bar nearly to end then gray screen.

Do you keep holding shift the entire time?

 

[Raz0rEdge]

If you know what version of macOS was running on that iMac, then create an USB installer with that which will at least put you into the installation terminal and see if you can use Disk Utility there to try to check/fix the drive. If not possible, then grab a new SSD and replace the built-in HDD and use the USB installer to install macOS on the new drive.

 

[IWT]

Nope, no boot in Safe Mode. Start+Shift - Logo appears then progress bar nearly to end then gray screen.

It may be regarded as too late to pursue Safe Mode; but for the record, Safe Mode often fails because if you are using a BlueTooth keyboard, that keyboard is not recognised until late in the booting up process. And Safe Mode needs to be initiated from the very start of the booting.

Thus, to overcome this, it's best if you can use a wired KB.

Or, if you have a modern BT keyboard, you can attach it via USB to the iMac - the same as you would to charge it - and that will work.

Ian

 

[vansmith]

I'll throw another option in here. Can you boot the machine in what is called 'verbose mode'? Unbeknownst to many, your Mac details all steps of the boot process behind boot screen (eg. the grey screen, the Apple logo, etc) but you can make this visible during boot. This can provide some insights that might be helpful here. To boot into verbose mode, simple hold down Command-V once you start the machine from being turned off.

If you do that, can you post the last few lines here for us (those that appear once the machine gets stuck or stops booting)? Part of me thinks this isn't a HD issue but a software one.

 

[juicer52]

@vansmith. I am hopeful that it is sw but hope isn't a strategy ;-)
Verbose FLIES by and then goes to gray screen. I actually tried to take pics of it when it VERY briefly lagged but even that was blurry. I ran Cmd+S single user mode and /sbin/fsck -fy and the results report that the drive appears to be OK.
Ignored the MAC for a couple of days but then hit the power button and IT'S ALIVE... but NOT SO FAST buckaroo!
Rebooted it from an external High Sierra drive and ran Disk Utility and all discs read OK.
Rebooted in Recovery Mode Cmd + R and all discs read OK.
Rebooted from Cmd + D and no hardware problems found BUT just when I thought all was well, it shut down. Screen going gray with lines. Then black.
If it ever comes back to life, is there a way of seeing where the last "panic" occurs? How can I access this information?
Right now it is back to where I was a few days ago.
No boot from Safe Mode (holding the Shift down until logo and progress starts and also hold Shift down until it nearly completes and then goes to gray screen)
It won't boot to HS external drive, it won't boot in Safe Mode, it won't boot with a usb High Sierra installer. After chime, Cmd+R gives logo and progress but then gray screen. Option+Cmd+R gives the spinning globe and then progress bar but goes to gray screen. Since High Sierra is no longer maintained in the store/library, would that last option succeed anyway?
All the while if I insert a live Linux Mint 20 CD it runs flawlessly, ?bypassing the HD but using the hardware.
There is a separate boot / SSD and a 2TB storage HDD.
I really want to get MacOS up and running for my friend. This is a challenge since for me, installing Linux is an option but not for the owner.
I have an 800 to 800 firewire coming in a day or two to offload 750GB of pics from the storage drive. Early on I was able to upload the pics and docs from the boot drive to Amazon storage.
At that point, I guess I could try to reformat and reinstall High Sierra over the firewire from her spare 27" iMac running High Sierra as well.
All thoughts and suggestions appreciated.

 

[vansmith]

If the Linux live CD sees the drive and doesn't suggest any issues (although I'm not sure it can do much with a HFS+ formatted filesystem), then this lends some validity to the conclusion that the hardware is fine.

I'm a little out of options here, particularly if you can't boot from an external USB drive. That should operate similarly to a Linux live CD in that the boot system is external to the one from the internal drive (which of course makes sense).

Random question: are you sure that the High Sierra USB drive works? I'm confused as to why that doesn't work.

 

[juicer52]

100% sure the external Mac High Sierra HD works. I had already tested it on the spare 2009 27" iMac and then when the troubled Mac had risen from the dead, I booted from it to check the internal HDs using the Utilities program.
Don't be a quitter ;-)
I have spent a ridiculous amount of time on this project. No former Mac experience. Numerous calls to Mac support, a trip to the Genius bar. Countless postings on forums and reading in what at times seems a foreign language.
Still, I want to understand.