osihara
Level 1 (8 points)
iPhone

Q: iMac, "cannot mount root error" occurs during safe boot

During a "safe boot" I get the error "cannot mount root error" occurs. The iMac will not boot under any HDD including recoveries. Tried replacing HDD but get the same result. I normally get the disallow icon. But sometime I get the grey pa with a progress. It starts fast and gets slower and slower until it stops and sits there. Once I left it there for a couple of hours. Having already got the iMac apart i took the display off and the platter HDD was really HOT.

 

Background - This is a Mid 2009 24" iMac that is used as a home iTunes server. It was using it with one of our Apple TV's, paused it, and when I came back it had lost its connection with the iMac. So I checked iMac and it was running, Mouse woke the display but nothing else would happen. So I rebooted and that was that.

 

Just to add that it runs a home setup fusion drive consisting of 1 tb platter drive that came with it (think that size is right) fused with a 60 gb SSD. My first thought was it was either a failed group or one of the drives had failed. But with a new blank apple formatted drive I was still unable to boot into recovery. I noticed that the entire time I have never seen the network menu appear. I tried all the boot commands I can find. I can't get access to an online recovery or a hardware check etc. I have refreshed the NVRAM a few times with no change. Removed 1 RAM chip and refreshed again.

 

I can find plenty of people asking this question but no answers. Best I get are suggesting starting from recovery or something etc. which just won't happen. I can't find anyway to replace the EFI. I'm assuming either a component has failed or the EFI has corrupted.

iMac, OS X Yosemite (10.10.3), 24inch, v9,1

Posted on May 16, 2015 5:09 AM

by osihara,Solvedanswer
osihara osihara
Level 1 (8 points)
iPhone
A:

Ok, after a long wait I tackled the issue again. I removed all drives, performed SMS NPRAM power cycled and it finally booted into the recover stick. After that things went much better since I was able to access more than a blank screen or unresponsive icon. I connected the fusion drive pair to my main iMac and found the platter drive to be damaged. I destroyed the group and reformatted both drives. My iMac seemed happy with that. So put just the platter back into the old iMac and Disk Utility there reported it to be unfixable. So I have put a spare smaller platter drive in and used the SSD for another device and reinstalled from backup and all is back to normal.

Posted on Jun 11, 2015 10:36 PM

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osihara

Q: iMac, "cannot mount root error" occurs during safe boot

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  • Helpful answers

  • by osihara,

    osihara osihara May 17, 2015 12:23 AM in response to osihara
    Level 1 (8 points)
    iPhone
    May 17, 2015 12:23 AM in response to osihara

    Anyone have any ideas? Must be a tech out there with some genuine information.?

  • by Mike Sombrio,

    Mike Sombrio Mike Sombrio May 17, 2015 8:51 AM in response to osihara
    Level 6 (17,233 points)
    Apple Watch
    May 17, 2015 8:51 AM in response to osihara

    Have you tried restarting with your original gray install disc and running Disk Utility? EFI corruption is usually indicated by a series of tones at startup, 3 long - 3 short - 3 long Mac computers: About startup tones - Apple Support  You can check to see if there's an EFI update for your iMac EFI and SMC firmware updates for Intel-based Macs - Apple Support

  • by osihara,

    osihara osihara May 18, 2015 1:41 AM in response to Mike Sombrio
    Level 1 (8 points)
    iPhone
    May 18, 2015 1:41 AM in response to Mike Sombrio

    I wouldn't have a clue where that disc is... But it's irrelevant because the Optical drive died years ago. It doesn't even have the mechanism in it because I swapped it for a SSD last year.

     

    I don't get any tone just a partial boot. I get the same behaviour when booting from a recovery USB drive.

     

    See no indication of an update recently. I keep/kept the iMac up-to-date anyway.

     

    So I'm guessing it's trash now?

  • by osihara,Solvedanswer

    osihara osihara Jun 11, 2015 10:36 PM in response to osihara
    Level 1 (8 points)
    iPhone
    Jun 11, 2015 10:36 PM in response to osihara

    Ok, after a long wait I tackled the issue again. I removed all drives, performed SMS NPRAM power cycled and it finally booted into the recover stick. After that things went much better since I was able to access more than a blank screen or unresponsive icon. I connected the fusion drive pair to my main iMac and found the platter drive to be damaged. I destroyed the group and reformatted both drives. My iMac seemed happy with that. So put just the platter back into the old iMac and Disk Utility there reported it to be unfixable. So I have put a spare smaller platter drive in and used the SSD for another device and reinstalled from backup and all is back to normal.