Since Update 10.12.4 MMY External Hard Drive Won't Mount on Restart

The drive was plugged in during updating. Maybe it would have been better to unplug it, but it was plugged in while all updates over the last years and I never had a problem.

I hope there will be a fix for this in a future update.

My affected drive is connected via TBolt, not USB, so the problem clearly affects external devices on at least those two types of interface.

Until the 10.12.4 update the disk always mounted just fine on reboot, so the problem was introduced by the update.

It's the drive I am using for Time Machine at present, so mounting at boot time is useful (to say the least), and if it doesn't mount at boot time then there's a risk of important (to me, anyway) stuff not getting backed up in a timely manner.

...and telling the desktop to sleep rather than shut down is not a safe option when there's a significant risk that the power will go out.

Seems to work for the next login (MacPro,late 2013, 2 Thunderbolt discs (LaCie) with various partitions.

Still to be checked whether tis is going to work for a longer time. Sometimes all partitions were mounted automatically, sometimes not. So I set up a script to mount all partitions using diskutil. Sometimes this did not work. All partitions showed up in system profile, read-only if not automatically mounted. Then I found that it helps to unmount a partition first and mount then. In rare cases unmount produced an error. Then unmount again (OK), and then mount and there was the disk. So finally my home-brew solution was unmount all portions, mount all partitions, unmount all portions, mount all partitions and so far this worked always.

Note: Unable to reproduce, but started immediately after 10.12.4. Must be a problem with 10.12.4.

If you performed the Terminal command and nothing happened then your WD may have failed. These are inexpensive enclosures to begin with and prone to failure. I would recommend replacing it with a higher quality enclosure such an OWC (www.macsales.com) Mercury Elite Pro series.

Good luck.

This worked for me. Thanks. Worked with Apple support for two days. They had me create another user account to test some things and it looked like problem had to do with auto login change in 10.12.4. Then I saw your terminal command. Told Apple support about it. You should work for them.

10.12.4 is extremely stable, I suspect the issue is with your installation. If you want to post an EtreCheck report we can look for obvious issues. Click the link, download and run the app and copy and paste the entire results as your reply to this message.

Since some folks are saying that 10.12.5 fixed the auto mount of external hard drives problem, can you tell me how to reverse the sudo command of sudo defaults write /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin -bool YES

That helped me with the autodiskmount problem but has caused issues with super duper-I think. At any rate, I would like to try to undo this command so that I can see if external hard drives now mount automatically without that terminal command. I tried bool NO but I am not sure that did anything. When I run the plist in terminal I get AutomountDisksWithoutUserLogin = 0 Is that what it should be? Thanks

Hi Mrcrom,

I'm having a similar issue. I've posted elsewhere in here but have not gotten a real response:

I have two different WD external My Book drives (slightly different models) connected to a late 2013 iMac running Sierra, and both drives appear to function normally during the day. Every morning I wake up to a notification that tells me that Time Machine has failed on one of the two My Books (with the last successful backup usually occurring between 11:30pm and 1:30am). Then, if I go into either My Book, they both appear to be completely empty. (Sometimes a few folders will show up in the main directory, but they'll be empty of all files.)

WD Utilities will not run on the drives at this time. Unplugging them does not resolve the issue. Sometimes the drives show up multiple times in Disk Utilities.

The Mountain program is unable to unmount the drives (it says they are "in use") or remount the drives when they are in this condition. It gives the "force remount" option, which it claims may damage the content, so i don't do it.

*Only a full system restart, along with physically unplugging the external drives, and then remounting with mountain after startup, resolves the problem -- which then recurs overnight.

I have an external Seagate drive attached that does NOT suffer this problem.

As far as I can tell, my WD drivers are current.

I believe this problem started after I updated to Sierra, though I'm not positive. It was happening on 10.12.3 and 10.12.4. I just updated to .5 and there was no change.

This feels like a dangerous problem that I don't want to have repeated every night for infinity on drives that are supposed to be protecting my files.

I have tried turning off hibernate mode in terminal- this sometimes works for one day, but the problem recurs the following day. I am having trouble repeating the success.

Is there anything I can do about this besides replacing these drives with non WD-drives from now on? I purchased one of these drives a mere week ago to replace another one that I THOUGHT was failing, but was probably suffering from a similar issue. While I currently have three drives attached, I actually have five drives total, as I've been trying to sort through this issue: three wd, one lacie (part of wd, right?) and one seagate, and the ONLY one that's working is the seagate.

Further info as follow-up to questions: I did reformat the drives (and one of them is brand new, purchased two weeks ago, and reformatted), with no change in the situation.

The same problem is happening in two other drives that are not currently plugged in: A Lacie and another WD.

Does it not seem like there's an issue with the way the OS is communicating with these drives? And the fact that it's something that happens once per day, some time overnight seems to indicate that it's based on some kind of OS command and not based on enclosure or connection problem.

Time Machine works fine during the day, until the drives fail each night over night. It's not just the time machine drive that's failing. The other WD also shows up as empty, and unable to eject because it's "in use" like a frozen ghost.

Are there any terminal codes I could use to stop the drives from freezing up once a day, at basically the same time frame each day?

I could buy some more seagates I guess, but I literally have four working WD drives now that don't work seemingly just because of Sierra.

Thanks so much for any help.

Jon

I have only a couple of comments regarding some of what you said:

1. How/with what did you "reformat" the WD drives?

2. There are no drivers needed for any external hard drive. Absolutely none. All they need is to be formatted - best way is to use Disk Utility - correctly for Mac which is Mac OS Extended (Journaled) and GUID partition scheme. As an aside, WD does not support booting up from some/many of their external drives.

3. I have no clue what this "WD Utilities" is or supposedly does, but it is not needed. A completely erased/blank external drive works just fine as long it is formatted and you are either using Time Machine or a cloning app or simply drag 'n drop files on it.

So, at this point, my suggestion would be that you reformat/uninstall any WD software/drivers, make sure that it is erased, and then start over with Time Machine to see if it works any better. I would also suggest that you visit the WD support website and check on any problems reported by others - e.g. a couple of years ago, the software installed on WD drives caused customers to lose all their data.

Thanks so much for the reply.

1. Disk Utility reformatted the drives.

2. One drive is just a few weeks old. I reformatted it and my older WD My Book drive as well. Mac Os Extended (Journaled) and GUID.

3. WD Utilities is just WD's version of Disk repair, I think. I'm not sure it actually fixes errors, but it tells you if the drive passes its tests. The drives pass the tests during the day and then fail the test after they go bad every night.

It is important to note that only one of these drives is a Time Machine drive. The other is simply another external WD My Passport For Mac drive with a bunch of files in it. It too fails every night (can't access any files until force ejection/reboot of computer). Also, two other WD drives fail every night the same way (I don't have them plugged in right now because I'm trying out new drives that are having the same issue).

This clearly appears to be some kind of issue whereby my OS is forgetting how to communicate properly with WD drives; what's weird is how it happens overnight only. So I would've thought that fixing the hibernation setting would address the problem.

Sorry, but I'd rather lean to the thought that there is a problem with your WD drives (since you said that another worked fine). I'd uninstall (or rather erase) the WD drives to get rid of the WD software. I'd also check the WD support site and check if there are any reported problems with the chipset used in their cheap enclosures. That is quite often the cause of such problems and WD's are not known for their quality (the actual hard drives are ok, but the chipset in the enclosure is what makes the connection work).

I find it hard to believe that four WD drives would basically go bad all at the same time as soon as I updated from Mavericks to Sierra, but if that's the case, which drives would you recommend instead? Seagate only? Is there another reliable brand that works with Sierra?

I already reformatted the drives and there was no change in the nightly freeze-ups.

There was never any WD software on the drives themselves. It was on the iMac, where it had been for several years on Mavericks, and there were no negative issues with the drives. That said, I am erasing the software from my iMac.

I checked repeatedly with WD already and they insist the My Passport drives are working properly since they work normally during the day and only break will the Mac is asleep overnight (they do not break if the Mac is asleep during the day, however!). They blame a Mac OS issue. No one will take responsibility for the communication errors between the Mac and the WD drives.

Do run this test while hooked up to an older OS version if you can (just in case my theory (guess??) with the OS update/chipset issue might be relevant. My problem with the drives was in January last year and - if I remember correctly - I had updated to Yosemite or El Capitan before that (I rarely run the latest OS on my main machine due to some need for some older software).