High Sierra upgrade failed and left iMac unable to boot

[philb2611]

HI guys

2010 Imac , been working daily without any issues until latest upgrade,
Then after downloading and going through the install process i got the following message



Unfortunately when you restart its goes through the same process each time
Ive tried booting in recovery mode / internet mode and from a USB
but when i try to do disk first aid, it gives me errors it cannot fix and when I try a new install from that im told I've got smart errors so it cannot install. Disk utility tells me that I've got 450gb of data so I'm hoping thats its all still there





Now im usual pretty good at doing back ups and was planning to replace the Imac soon anyway but as fate would have it i've not back up in the past few weeks so would really love to be able to get into somehow. Anyone got an ideas. I read that some SMART error can be overcome but because i cannot get into the computer I can't do anything.

 

[Honza1]

Sounds ugly. I do not know iMac 2010, but if it is possible I would extract the drive, put in external (USB) enclosure and try to mount it to working Mac. Least destructive process. Power up/down as little as possible, every cycle may bring it closer to death... SMART means it is drive hardware which is failing.
If it mounts, copy data off the drive and throw it away. Drives are cheap. Replace with SSD and it will be much better.
If it does not mount, may be someone can suggest user friendly software which may help... I used once ddrescue to clone bit-by-bit the drive to different (new) one and it (luckily) worked even when original drive failed to mount due to hardware failure. It took 3 days and was pain to deal with. But saved the day.
As you realized by now (as well as I did!): Backups are critical. Every drive will fail, it's just question when.

 

[avinator]

So....do you at least have an old backup? Try to boot from that...
I've been using super duper forever now and it saved my behind a bunch of times...


Alternative install

Install OS X on an external drive...
Boot from that drive and try to mount your old drive
Copy data to external drive.
Use super duper to clone external drive to old , “broken “ drive.
Retire your drives every 24 months

 

[philb2611]

I've got a time machine back up on an external HD. Guessing you cannot boot from that? Last back up was about 6 weeks ago. Could I connect another Mac via firewire and use it as target disk?

 

[TimothyR734]

Yes you can install macOS on a external hard drive but you would lose your time machine backup if you use it to install macOS

 

[dianeoforegon]

• Boot into the Recovery drive with an external drive attached.
• Open Disk Utility and format the empty external drive as GUID, HFS+ Mac OS Extended Journaled
  
• Quit Disk Utility
• Select to reinstall macOS on the external drive.
• After the install, you should boot from the external drive. this will allow you to see your data on the internal drive. You can manually drag over your data to the external or partition the external and select to clone the internal to the new external partition.

Software used to Clone:

CarbonCopyCloner http://www.bombich.com/download.html (All options are available free for 30 days)

SuperDuper! http://www.shirt-pocket.com/ (Free forever to do an erase and install. Purchased version allows for smart updates and schedules)

 

[amaze1499]

So....do you at least have an old backup? Try to boot from that...
I've been using super duper forever now and it saved my behind a bunch of times...


Alternative install

Install OS X on an external drive...
Boot from that drive and try to mount your old drive
Copy data to external drive.
Use super duper to clone external drive to old , “broken “ drive.
Retire your drives every 24 months

What he says. Actually, get a new HD or SSD. Put it in, install a system onto that one and then connect the old drive to copy whatever you can.