Q: Internal/Startup Disk missing, then reappears
I apologize for the long post, but its length reflects the amount of time I've been chasing this issue over the last 3-4 weeks.
Anyone experiencing their Internal / Startup Disks disappearing after installing OS X Yosemite Recovery Update 1.0 and Bootcamp / Windows 8.1, making the computer unable to boot?
I found this Apple Support bulletin (If a flashing question mark appears after installing 'OS X Yosemite Recovery Update 1.0.' - Apple Support), but my configuration is different - I have FileVault full disk encryption enabled, but do NOT have a firmware password set.
When I say the Internal/Startup Disk is missing / has disappeared, I mean:
A) computer boots to flashing icon of folder with question mark in it
B) internal disk does not show up when boot to Startup Manager (hold Option during Startup)
C) internal disk does not show up when booting under OS X Internet Recovery and then accessing Startup Disk utility
D) internal disk does not show up in Disk Utility after booting to an external Startup Disk
E) internal disk does not show up in Install OS X Yosemite as a destination disk after booting to an external Startup Disk (was thinking I could reinstall Yosemite)
Also reset NVRAM (Command+Option+P+R) during these many reboots.
From terminal, appeared the internal disk was not mounted, but I can not confirm this now (what is best command line to confirm this?). I've probably missed a few other scenarios as I've rebooted the computer more than 50 times today in every way I can imagine.
This has occurred on 2 Macs within a week of installing OS X Yosemite Recovery Update 1.0 (around April 10 I think) - perhaps that is just a coincidence - and now a 3rd time on one of the Macs. I also associate the problem with Bootcamp / Windows 8.1 because it happened twice within 48 hours after installing Bootcamp / Windows 8.1.
#1) Late 2012 iMac, 3TB Fusion Drive, OS X 10.10.3, FileVault enabled, Firmware Password NOT enabled , Bootcamp / Windows 8.1 installed on 2nd partition.
Issue arose about one week after installing Yosemite Recovery Update 1.0 - did not happen immediately. Problem then arose. During rebooting it 10's of times trying to recover, the disk became corrupted, eventually requiring Apple Genius to reformat the disk. A week later after reinstalling 10.10.3 it was back at Apple and has now been there for more than 10 days. It is possible this iMac was also having hardware issues. Awaiting word from Apple.
#2) 2012 MacBook Pro, 500GB SSD, OS X 10.10.3, FileVault enabled, Firmware Password NOT enabled
One day after #1, the same thing happened to my MacBook Pro. It did NOT have Bootcamp / Windows 8.1 installed, but did have a 2nd partition with Preview of Yosemite on it. Was eventually able to get Startup Disk to reappear as described below. Perhaps the existence of the 2nd partition is the common factor here. MacBook then ran fine for 2 weeks until #3 below (today).
#3) The same MacBook Pro, 2 weeks later (today), 2 days ago after removing the Preview partition in #2, and installing Bootcamp / Windows 8.1
Rebooted 10's of times as described at top of this post. No joy! Then ...
Temporary Fix: I have been able to make the MacBook Startup Disk reappear after both #2 and #3 above. Found this by accident --- if I shut down the MacBook and unplug it from external power and let it sit for at least 1 hour - NOT just a few minutes - the Startup Disk and the 2nd Partition (Preview in #2 above, Bootcamp / Windows 8.1 in #3 above) reappears. I then rebooted successfully a few times and now typing this post on the MacBook.
This is incredibly frustrating, but will now resort to unplugging it for more than an hour if reoccurs. Hoping someone can confirm source of the problem so I can avoid that part of my configuration. Am thinking about eliminating the 2nd partition and switching Windows 8.1 to VirtualBox or Parallels for now as only need to run one lightweight app in Windows.
MacBook Pro with Retina display, OS X Yosemite (10.10.3), 500GB SSD
Posted on May 6, 2015 3:57 PM