troubleshooting Question

iMac Disk Utility First Aid Failed

Avatar of markbyrn
markbyrnFlag for United States of America asked on
Mac OS XApple OSApple Hardware
7 Comments2 Solutions12893 ViewsLast Modified:
I have an iMac 27" Retina 5K (Late 2015) El Capitan (10.11.2) and Windows 10 via Bootcamp.   This morning after I had finished some work on the Windows side of the machine, I tried to boot up into El Capitan but it silently failed and the machine turned itself off at about the 2 minute point.  Tried again and same problem.  So I checked if I could get back into Windows and ran Windows 10 with no problem.  Next I booted into the Mac recovery partition to run Disk Utility and it revealed an enormous number of errors on the Macintosh partition such as:

- Previous ID in a hard link chain is incorrect (ID = -1130612101)
(it should be 3164355194 instead of 0)
Many of the above errors appeared with different numbers
- Volume bitmap meds minor repair for orphaned blocks
- Invalid volume free block count
- Volume header needs minor repair
- Missing thread record (id = -1130634630)
Many of the above errors appeared with different numbers

Finally the process 'finished' with "First Aid process has failed.  If possible back up the data on this volume"

Next I booted into a USB installed version of El Capitan and while that was successful, it gave a warning when it mounted the volume that I was having the problem with: "OS X can't repair the disk 'Macintosh HD'" but I was able to copy files from that volume and even run applications that were stored on it.  Tried running Disk Utility and First Aid again but failed as above.

So here are the questions.

1.  Should I assume there's nothing else that can be done other than erasing that partition and reinstalling El Capitan?

2.  Will erasing the partition and reinstalling El Capitan affect my Bootcamp partition or ability to use Win 10?

3.  I have a Time Machine backup; will restoring it re-introduce the same problem?

4.  I've never had such a massive and unrecoverable failure on a Mac drive and I had used it the night before with no problem.  Should I assume the disk itself is faulty and have it replaced?  I ran an Apple Hardware Test and no problems were indicated.
ASKER CERTIFIED SOLUTION
strung

Our community of experts have been thoroughly vetted for their expertise and industry experience.

Join our community to see this answer!
Unlock 2 Answers and 7 Comments.
Start Free Trial
Learn from the best

Network and collaborate with thousands of CTOs, CISOs, and IT Pros rooting for you and your success.

Andrew Hancock - VMware vExpert
See if this solution works for you by signing up for a 7 day free trial.
Unlock 2 Answers and 7 Comments.
Try for 7 days

”The time we save is the biggest benefit of E-E to our team. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange.

-Mike Kapnisakis, Warner Bros