Single User Mode Help - External drive boots MPB but not iMac

IconicM

macrumors regular
Original poster
Jan 30, 2011
196
1
Houston, Tx
Hi,

I have been working on getting my iMac to boot with no success.

Initially the symptom was slow operation. This coincides with an attempt to upgrade the OS to 10.13. I was able to revert to the previous OS from a time machine back up, but the problem of being slow, snowballed at that point. Eventually got to where on reboot, I would get the white screen with no progress at all. I diagnosed this as a bad hard drive, which I had previously replaced a little over 2 years ago, 2TB Seagate SSHD.

At that point I thought, "no problem, hard drive upgrade". I upgraded the opti drive to a 500 GB SSD so I could load/ run OS X separately from the new WD 2TB hard drive. To get started, i left the HDD disconnected and only connected the SSD.

After several failed attempts of loading OS X onto the SSD, mainly through start-ip manager disk utility then tried at the command prompt. The system would get stuck on progress bar and would not finish. Could not get it done.

So I purchased another SSD, installed into external bay. Was able to load a new copy of Sierra onto it using my MBP. Using start-up manager, I was able to start my MBP with this external drive.

Then I connect it to my iMac, use start-up manager to select but still am not able to boot. Would get stuck on progress bar at about 75%.

Then I used disk utility to copy the OS from my external drive to the internal SSD. I was able to verify that the amount of space used was similar about 13.2 GB on both drives. Tried to reboot, and get the progress bar that gets to about 75%.

Next I reboot in Single User Mode. There is definitely an issue, because using /fsck command, get the disk modified. But on running /fsck a second time, volume is OK. So seems to be a single problem.

I tried to reboot, but again got stuck in progress bar.

Got into single user mode again, and ran /fsck. Same thing, single issue found. This time I "exit" to continue booting, but again, progress bar, this time no progress at all.

It seems the problem is not the hard drive but something else. I need your help to troubleshoot. I am not that familiar with Single User Mode, but willing to learn.


Thanks for your help in advance.
 

DeltaMac

macrumors G3
Jul 30, 2003
9,535
2,303
Delaware
With the SSD already in place on the iMac --- boot to your Sierra installer.
And, reinstall Sierra.
Does the install finish? It will be a 3 step process.
1. The installer copies all the files to your SSD.
2. Your iMac reboots, and the actual install happens.
3. The install completes, and you are returned to the desktop - or login screen. There would be quick login to your AppleID account at that end of the install.

Does all of that happen? If not, where does it stop? Give it plenty of time to finish. Might take 30 minutes, or could take a couple of hours.
Be patient... :)
 

IconicM

macrumors regular
Original poster
Jan 30, 2011
196
1
Houston, Tx
I went ahead and pulled the 500GB SSD from the iMac. I installed it into external enclosure and verified that I am able to boot into Sierra with my MPB that is running El Capitan. This verifies I have working Sierra on the 500 GB SSD.

The 250 GB SSD that I had previously used to successfully boot my MPB, again Sierra loaded on it, I installed that into the iMac. Again, same result on progress bar.

One correction, though: the progress bar stops at about 25% not 75% as I previously stated - did this with either SSD.

So I am now fairly sure that I have a hardware issue that is not drive related - probably a board or RAM? I am asking for help in troubleshooting this in Single User Mode. I am thinking that I should be able to narrow it down through the sequence of text prompts where the issue is??

Thanks for the help anyway DeltaMac!
 

DeltaMac

macrumors G3
Jul 30, 2003
9,535
2,303
Delaware
Good...
boot to single-user mode, then (if you can)
Run the fsck -fy command. That's a good place to start.

I would also suggest trying the built-in Diagnostic test. (Restart, holding the D key)
That won't test your hard drive, but it will run a simple test of the drive bus, which may show error.

Also - try booting your iMac to an external drive (could be the SSD that you know boots your MBPro), in an external case.
Be sure to try that with the internal drive disconnected. If that works, you may simply need to try replacing the internal SATA cable. I've not read about that as a problem with iMacs (usually in MBPro), but it's still part of the bus, and could fail due to handling. It's also a lot easier (and cheaper) than the other step, which would involve replacing the logic board. That might still be the fix, but I like to eliminate the easier (cheaper) choices first.
 

IconicM

macrumors regular
Original poster
Jan 30, 2011
196
1
Houston, Tx
OK some progress...

I am actually able to start in safe mode. The 500 GB SSD is back in and I am able to access safari, so I am assuming the rest should be good. I tried to restart in normal mode, but that gets me back to stuck on progress bar. Tried again in safe mode, and again able to boot up. Whew!! I can almost see the light.
 

DeltaMac

macrumors G3
Jul 30, 2003
9,535
2,303
Delaware
Try booting into "verbose" boot mode.
That is similar to single-user where you see text on the screen, but it continues to boot, listing some of the services as they load.
Restart, holding Command + v
watch for some text that begin to repeat, or that it stalls at some point. Come back here with the last 2 or 3 lines.
 

IconicM

macrumors regular
Original poster
Jan 30, 2011
196
1
Houston, Tx
I went to system preferences/ startup disk. The 500 GB SSD is the only device in there, but it will not let me highlight it as the startup disk.

Some of this looks a bit suspect so including a few more lines. It was really difficult to tell the deference between "0", "O" or "8". Also had a hard time with "i" vs "l". I tried to stay consistent.

** Device in slot: SLOT--1**
6.328223:apple00211Request [10514] Unsupported ioctl 156
Airport: Link Down on en1. Reason 8 (Disassociated because station leaving)
Got incomplete channel sequence length 8, should be 16
6.364156:apple00211Request[10514] Unsupported ioctl 181
HID: Legacy shim 2
unexpected session: 100000 uld: -1 requested by: 34
AppleKeyStore: Operation failed (pid: 34 sel: 7 ret: e00002c2 '-536870206', -1, 100000)
ACPI: Dynamic OEM Table Load:
6.483527: apple80211Request[10514] Unsupported ioctl 156
6.483922: apple80211Request[10514] Unsupported ioctl 181
Got incomplete channel sequence length 8, should be 16
ACPI: SSDT 0xFFFFFF0035A1F310 00047B (v01 PnRef CpuOIst 000030000 INTL 20061109)
ACPI: Dynamic OEM Table Load:
ACPI: SSDT 0xFFFFFF0034A6818 0006E5 (v01 PnRef CpuOCst 000030001 INTL 20061109)
ACPI: Dynamic OEM Table Load:
ACPI: SSDT 0xFFFFFF0035EC9810 0003A4 (v01 PnRef ApIst 000030000 INTL 20061109)
ACPI: Dynamic OEM Table Load:
ACPI: SSDT 0xFFFFFF00349C6610 000119 (v01 PnRef ApCst 000030000 INTL 20061109)
ApplePC::notifyPlatformASPM - registering with plugin with ASPM Support false
6.048118: apple00211Request[10514] Unsupported ioctl 156
[doublepost=1499655287][/doublepost]corrected the above from "00211" to "80211". I believe this has to do with wi-fi standard. I do have the ethernet cable plugged in.
 
Last edited:

DeltaMac

macrumors G3
Jul 30, 2003
9,535
2,303
Delaware
I think the reason that you can't select the boot drive in your Startup Disk pref pane, is that pane is locked since El Capitan.
So, go back into that Startup Disk pane, then click the Padlock in the lower left corner. That will unlock that pane, and allow you to change the selection.

Please review my post #4
Which of those steps did not work?
 

IconicM

macrumors regular
Original poster
Jan 30, 2011
196
1
Houston, Tx
DeltaMac, thanks for being so persistent to help. If you are ever in Houston, I will buy you a beer.

You were right about the startup disk, just had to unlock it.

Last night, I ended up connecting the 2TB HDD. I was able to load Sierra onto it using the iMac. Booted in safe mode, dowloaded OS from App store and installed it onto the drive. It seems to be a successful download of Sierra, but again, can only boot in Safe Mode. Normal mode not working with either drive, so I am guessing that the SATA cables are OK.


Good...
1. boot to single-user mode, then Run the fsck -fy command - I have done this a few times, and fsck does find one error, to modify each and every time I have run it. Of course I run fsck a second time, and it shows disk volume to be OK.

2. I would also suggest trying the built-in Diagnostic test - When I hold down D, the mac is not recognizing this because it eventually goes to the apple logo with progress bar and gets stuck. I made sure there are no peripherals connected except for the USB keyboard. Since that did not work, I tried option-D. Did not work either, did the same thing as holding down D.

3. Also - try booting your iMac to an external drive (could be the SSD that you know boots your MBPro), in an external
I tried this previously. The Mac will not boot with a known good copy of Sierra, either internally or externally connected. I know the copy of Sierra is good because I tested it by booting my MBP with it. I am thinking the SATA cables are good.
Problem is still that I am not able to boot in normal mode. The only way to boot is by holding down the shift key to boot into safe mode.


Thanks again.