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  1. #1
    Mac will not boot to correct disk despite being set as Startup Disk
    Hi all. I have an issue.

    I run the latest OSX on an external SSD connected to my 2014 Mac Mini via USB3.

    Yesterday I booted up and it booted to the internal disk instead. I checked the SSD and found that the SSD had been wiped - there was no data at all, it was as though it had been formatted. Luckily I always back up using Time Machine so I was able to restore from the last backup and got all my files & OS back onto the SSD so that was great.

    However I now find that I can't boot directly onto the SSD. It is set as the Startup Disk, however at boot it is not detected and my Mac always boots to the internal HDD. The SSD is detected once I've booted up and all the files are there. The only way I can boot to the SSD is to disconnect it, reboot while holding Option to get into the boot menu. I then connect the SSD and it appears in the list and i can now boot from it - it works fine and all my data is up to date. However next time I restart, it boots straight into the internal HDD again. It is as though the Mac is not detecting the SSD at boot time, so always uses the HDD. If I don't disconnect the SSD before I restart, holding down Option key has no effect - it ignores it and boots straight into the HDD. I have checked that the SSD is set as the Startup Disk when I'm booted into both the SSD and the HDD, it makes no difference.

    Does anyone have any ideas what's going on?

    Thanks!

  2. #2
    Mac will not boot to correct disk despite being set as Startup Disk
    ferrarr's Avatar
    Member Since
    May 21, 2012
    Location
    Pawtucket, RI, US
    Posts
    5,332
    Your Mac's Specs
    L2014 Mac mini macOS Mojave, iPhone 8+ iOS 12, 12.9" iPad Pro 1 iOS 12, Pencil 1
    If you open Disk Utility, what format is the external SSD? Mac OS Extended (Journaled) or APFS? And which specific version of OS X/macOS are you using? 10.10, 10.11, 10.12, 10.13, or 10.14?
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  3. #3
    Hi Bob
    It's an OS X Extended partition. Bootable and Journaled.

    OSX version is 10.14

    Thanks

  4. #4
    Mac will not boot to correct disk despite being set as Startup Disk
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Keller, Texas
    Posts
    56,761
    Your Mac's Specs
    2017 27" iMac, 10.5" iPad Pro, iPhone 6s+, iPhone 7+, Numerous iPods, Mojave
    You're using Mojave so the SSD will have to be formatted to APFS in order for it to be recognized when you boot the Mini. You will have to copy everything off the SSD, format it as APFS and then install Mojave to it.

  5. #5
    Mac will not boot to correct disk despite being set as Startup Disk
    pm-r's Avatar
    Member Since
    Oct 16, 2010
    Location
    Brentwood Bay, BC, Canada
    Posts
    10,223
    You will have to copy everything off the SSD, format it as APFS and then install Mojave to it.

    Just out of curiosity, if a macOS Mojave install can change the format structure on an internal boot drive without doing a backup etc., why can't it do the same thing with an attached external drive??

    Or did they just not include such a feature which would seem odd to me, or would a reinstall allow that option to be used if the external was used as the booted drive???





    - Patrick
    ======

  6. #6
    Mac will not boot to correct disk despite being set as Startup Disk
    MacInWin's Avatar
    Member Since
    Jan 01, 2009
    Location
    Winchester, VA
    Posts
    4,921
    Your Mac's Specs
    MBP 15" Mid 2015, iPhone XS, an iMac, plus ATVs, AWatch, MacMini
    Patrick, if you follow the sequence that led to this dilemma, the drive was wiped accidentally, probably formatted to HFS+ in that process, then restored from a Time Machine backup. So it was not then bootable because of the HFS+. Had he reinstalled the OS instead of restoring it, it would have converted the external drive. I have one done that way as a backup bootable clone. So Apple *did* include the feature and it does work. Just in this case, the sequence of events led to a non-bootable HFS+ restored external drive that now needs to be converted to APFS.
    Jake

  7. #7
    Mac will not boot to correct disk despite being set as Startup Disk
    pm-r's Avatar
    Member Since
    Oct 16, 2010
    Location
    Brentwood Bay, BC, Canada
    Posts
    10,223
    Thanks for the clarifications Jake.

    PS: Just got back from the annual do where my old employer put's an an "English High Tea" for all retirees who RSVP'd they would like to attend. So I guess I didn't read the original post that carefully.

    PPS: Some nice strong rum and eggnog helped balance the Tea when I got home for a treat.






    - Patrick
    ======

  8. #8
    Mac will not boot to correct disk despite being set as Startup Disk
    MacInWin's Avatar
    Member Since
    Jan 01, 2009
    Location
    Winchester, VA
    Posts
    4,921
    Your Mac's Specs
    MBP 15" Mid 2015, iPhone XS, an iMac, plus ATVs, AWatch, MacMini
    Heh! Patrick, I guess if you were set for strong rum and eggnog and got tea, that would be a shock. I do like to go to tea with my lady, and we do it regularly when we visit England. She was a tea merchant at one time, but sold the retail business and now restricts herself to wholesale to tea rooms and vintage items to the general public. So we like to see how well the US tea rooms do when compared to English tea rooms. Generally not too bad. Where was your tea, the Empress? I wasn't impressed last year when we had tea there. Thought it was average and a bit overpriced.

    EDIT: Oh, yeah, you worked at Buchart Gardens, right? I bet that's where it was. Lovely place for a do.
    Last edited by MacInWin; 12-06-2018 at 01:03 AM.
    Jake

  9. #9
    Mac will not boot to correct disk despite being set as Startup Disk
    pm-r's Avatar
    Member Since
    Oct 16, 2010
    Location
    Brentwood Bay, BC, Canada
    Posts
    10,223
    EDIT: Oh, yeah, you worked at Buchart Gardens, right? I bet that's where it was. Lovely place for a do.

    You have a good memory Jake, and yes I worked there for fourty years. And actually lived in one of the houses they had on the property for 30+ years.





    - Patrick
    ======

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