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Large hard drives won't mount after restart in Mac Pro 2012

This post closely follows a previous thread: 6TB drives won't mount after restart in Mac Pro 2012

I have had a very similar problem with a Mac Pro 2012, running either 10.10.5 or 10.13.3 off a SSD. Upon restart or Option-restart, the system will not mount the following disks:

6TB WD Black WD6002FZWZ

8TB HGST He8 HUH728080ALE600

8TB WD Red (white labeled OEM version WD80EMAZ)

Other details:

- On cold boot or option-boot, all of these drives will mount, and all the drives work great.

- Two different systems are affected exactly the same way: Yosemite HFS on SATA 3 sled or High Sierra APFS on PCI card.

- None of the drives are formatted involving a Logical Volume Group (this was a red herring in the last thread).

- One of the effected drives (WD Red) has a 2TB partition with Yosemite on it. Upon option-restart, this partition shows up on the option screen and is selectable. If selected, the system gets part way through startup, then a grey circle with line through it appears. This would seem to imply the problem is not a time-out waiting for the drives to spin up as has been suggested in the previous thread. Rather something is causing the drives to shut down or unmount part way through startup (including the startup partition).

- 2 of the 3 drives are SATA 3.3 compliant and have a remote power-off on pin 3. But in all cases pin 3 is manually taped off (and the problem does not occur on cold restart), so I am sure it is not a PWDIS issue.

Posted on Mar 30, 2018 10:54 AM

Similar questions

23 replies

reldauts Author

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Mar 30, 2018 10:25 PM in response to Grant Bennet-Alder

If the startup drive became unmounted part way through startup, would this not also explain the appearance of a prohibatory symbol? (Can't find files if the drive is dismounted).

Mar 31, 2018 5:19 AM in response to reldauts

Yes, but that does not make sense.

Why would a drive that is spinning and ready and has already been providing data suddenly go not ready and refuse to perform?

Mar 31, 2018 8:07 AM in response to reldauts

There is no safety Interlock for the side door.

Do not put your fingers in the fans, or touch Processor components that may be HOT.

reldauts Author

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Mar 31, 2018 1:14 PM in response to reldauts

reldauts Author

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Mar 31, 2018 1:19 PM in response to reldauts

Wow, those images are crap after compression. Here are zooms.

reldauts Author

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Mar 31, 2018 4:41 PM in response to Grant Bennet-Alder

Agreed.

But now we are back to the simpler question that started all this. Why are these three 6TB+ hard drives not mounting on restart!

reldauts Author

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Mar 31, 2018 6:26 PM in response to Grant Bennet-Alder

OK, let's go with this as a working hypothesis. Can you think of anything I can do (at the user end) to insert delays into the restart sequence to give more time for the drives to spin up?

Mar 30, 2018 2:55 PM in response to reldauts

The solid Apple is not in the Mac's ROM at startup. The Apple logo can only appear when it is fetched in the first "blob" of software loaded from a 'magic' place on the boot drive. Then a whole lot of stuff is initialized, and the progress Bar moves part way across. Seeing the solid Apple appear says your drive is not completely dead.

The next step requires a lot of files by name, so the File System is initialized, and the Boot Drive is Mounted. If the drive directory is damaged, the drive can not be Mounted, so your Mac begins one pass of Disk Utility Repair. This will take an additional about five minutes. During this process, the progress bar may be extended, and will grow by an additional amount not seen on a routine startup.

If you get the Prohibitory sign at this point, it indicates some of the components of MacOS are damaged or missing.

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Large hard drives won't mount after restart in Mac Pro 2012