Hard drive will not unmount with Disk Utility - How about Single User Mode?
 

Hey all, this is my first post with you guys, I have a Macbook Pro 2012 running Mavricks that has decided to quit booting up normally. So I booted off a USB drive I have set up as an emergency start-up drive and tried to repair the drive. Says I'm outta luck and need to reformat, no problem I'm backed up and ready to go... but then the drive will not unmount to be reformatted in Disk Utility and the partition can't be mounted.

I am in the Amazon in Peru and I don't have a fire wire cable so targeted disk mount is out but I can boot into Single User mode. Problem is my unix command skills suck and I don't know how to identify the correct drive and then zap it clean using SUM command line prompts. I have a feeling that once I get the drive wiped I will be able to restore from back-up. Any help greatly appreciated.

1) Are you sure you booted from the external USB drive?

2) You don't normally need to unmount a disk in order to reformat it in Disk Utility (provided it is not being used)

3) There are utilities that will tell you which files (if any) are being used on a disk. I recall also a "Hint" on the main site that explained how to find out what was keeping a disk "busy".

Donationware "What's Keeping Me?"-- http://www.hamsoftengineering.com/products/wkm/wkm.html --is one such utility.

Yup, definitely logging in from the USB. It was running so slow that I reformatted another external 1TB drive to use as a start-up drive (much faster!) and got the same results (disk would not unmount). This occurs in the command-r mode as well. Nothing seems to be able to penetrate this drive.

One interesting thing, in the info area of the DU it says that the drive is not ejectable. Why would that be? This is my internal drive that has functioned as my system drive for two years! I have further isolated the problem to the partition, not the main drive. The main drive passes all validation both with Disk Utility and Techtool Pro, but the partition fails and cannot be mounted. Really frustrating.

I'll try the disk busy utility mentioned, but I was thinking there was a way to force a wipe through the single user mode. I thought that with some fancy Unix commands I could just zap it clean and reformat. Wishful thinking I guess.

If I should encounter an offending file that is keeping the main drive busy (could it be coming from the partition?), how do I kill it?

Again, thanks in advance for any help and muchas gracias for the replies thus far!

Here is some additional info which may be helpful...

THIS IS THE INFO ON THE MAIN DRIVE

Name : APPLE HDD HTS547550A9E384 Media
Type : Disk

Partition Map Scheme : GUID Partition Table
Disk Identifier : disk0
Media Name : APPLE HDD HTS547550A9E384 Media
Media Type : Generic
Connection Bus : SATA
Device Tree : IODeviceTree:/PCI0@0/SATA@1F,2/PRT0@0/PMP@0
Writable : Yes
Ejectable : No
Location : Internal
Total Capacity : 500.11 GB (500,107,862,016 Bytes)
Disk Number : 0
Partition Number : 0


THIS IS THE INFO ON THE PARTITION

Name : Little Ruckus
Type : Partition

Disk Identifier : disk0s2
Mount Point : Not mounted
File System : Mac OS Extended
Connection Bus : SATA
Device Tree : IODeviceTree:/PCI0@0/SATA@1F,2/PRT0@0/PMP@0
Writable : Yes
Universal Unique Identifier : 5E383E51-65A2-3605-AE52-A0F94516E50C
Capacity : 499.25 GB (499,248,103,424 Bytes)
Owners Enabled : No
Can Turn Owners Off : Yes
Can Be Formatted : Yes
Bootable : Yes

1) I think "ejectable" just means physically ejectable - so obviously your internal drive is not ejectable.

2) There is very probably a way to format the drive using Unix commands - but it's easier to do it using the GUI utilities and the same problems will need to be solved (understood) in any case.

3) When you say that the drive "passes all validation" with Disk Utility - what exactly have you tried? I presume in Disk Utility you are doing "Repair Disk" - not "Repair Disk Permissions" and not "Verify Disk" - is that correct?

4) It might be helpful if you showed us a screen capture of the Disk Utility window.

Yes I have done a number of "Repair Disk" actions, which obviously "Validates" or "Verifies" the disk if there are no errors, which there are none on the primary drive.

i'll set up the screen shots next. Thanks for the interest and help!

Oh, BTW, tried the utility that macosnoob suggested... it couldn't find the drive. I suppose it should be mentioned that the drive does not show up on the desktop or in any Finder window, ever, even though it is supposedly mounted and can't be unmounted.

When booted from the external, try in Terminal

diskutil mount "Little Ruckus"

and/or

diskutil mountDisk "Little Ruckus"

Anything?

Screenshots of the Disk Utility window should be a priority so we can see what might be going wrong.

Be sure to include one that shows the messages after doing a "Repair Disk"

You unmount volumes; you eject drives.

In the following I will sloppily equate volume=partition. (A partition becomes a volume when you put a filesystem on it; a single RAID volume will span multiple partitions. I'm ignoring those niceties.)

When you select a volume in Disk Utility, you will see an option to "Unmount" if the volume is unmountable. (The boot volume not unmountable. You will also be unable to unmount a volume that has any open files on it, but Disk Utility won't check that until you try to unmount it. Until then, it considers the volume potentially unmountable, and enables the "Unmount" button.)

When you select either a drive or a volume in Disk Utility, you will see an option to "Eject" if the drive is ejectable and all of its partitions are unmountable. (An internal drive is not ejectable.) Ejecting a drive implies first unmounting all of its partitions.

You don't need to eject a disk to reformat it. (Quite the contrary. Once you eject a disk, you can't do anything with it, because it's no longer there.)

Disk Utility will let you erase a volume whether it's mounted or unmounted. (If it's mounted, it will be implicitly unmounted before the erase can proceed. If the unmount fails, so does the erase.)

I notice Disk Utility will also let you erase a drive if all of its volumes are unmountable. I assume that implies unmounting all of them, then repartitioning as a single volume.

OK, some screen shots showing the repair results of the drive and volume the attempts to erase both and a shot of the drives that show up on the desktop. Hope this helps.

and three more...

diskutil mount "Little Ruckus" resulted in...

Volume on disk0s2 timed out waiting to mount.

What happens when you select the device line (500.11 GB … line, not the Little Ruckus line), then Partition tab, choose Partition Layout, then change to 1 Partition?
Continue by naming the partition, if you like, then click the Apply button. That's a step that should clear the partition info, and may complete this time… Should only take 5 or 10 seconds, at the most.

The screen shots you showed indicate that the "Recovery HD" is okay.
(The recovery partition is for booting from when your main disk is bad)
But for the main disk volume that you are interested in it said "Can't repair".

I mention this just because you had earlier said that Disk Utility seemed to give your hard disk a clean bill of health.

The above confirms that what you want to do is reformat (erase) the main disk partition and restore from your backup.

Yes, I have tried this a number of times with 1, 2, 3... partitions. All result in the failure due to the disk not unmounting.

OK, the result when repairing the main drive has no error messages and yes it says the "Recovery HD" is okay. I figured that means the main drive is fine.

And yes, I absolutely want to reformat and restore the drive, just can't seem to get there!

Or more accurately, erase and restore the partition on the volume, but that partition is damaged and can't be opened and when I try to re-partition the drive it gives the can't unmount error -6888

Here's a partition attempt result...

Are you equipped to remove the internal HDD and put it in an external enclosure? If so, I'd

1. Put internal 500GB HDD in external closure.
2. Boot from your 1TB HDD.
3. Use Disk Utility to reformat the formerly internal 500GB HDD now in the external closure.

I truly don't know that this procedure will help. I offer it as another way to reconfigure the items you may have available to you. "Little Ruckus" may remain unmountable whether it's internal or external.

To be honest, I'd likely just replace the HDD with a new one, though I can appreciate that, given your current location, it may not be possible.

Well looks like we have collectively hit a wall here. Maybe someone could speculate on what could be making the internal drive too busy to un-mount even after multiple re-boots to other/external drives with current system software running. I can't figure out how a rogue file or process could start up so consistently that it can't be interrupted in some way (either during spin-up or by doing some kind of general kill command via the Terminal). This is all way above my pay grade, but I'm a good learner and I am now just curious what the heck is going on here more than anything else.

Is it possible that it is a hardware problem that just makes it look like it is busy, even though it passes a repair process with Disk Utility? I dunno, it's driving me nuts.

Yeah, I don't really have a place to get this done that I know of. I am going to look around some of the shops here and see if I can dig up a firewire cable or an enclosure to see if I can spark it up as you suggest. I'll let you know ;)

"Is it possible that it is a hardware problem that just makes it look like it is busy, even though it passes a repair process with Disk Utility? I dunno, it's driving me nuts."

Failing HDDs are quirky. While what you report seems to be the kind of thing that can be fixed with software, the fact that software isn't fixing the trouble makes me wonder about a hardware issue. In the US, a new 500GB HDD is around $60--a small price to pay to preserve sanity and get back to work. You'd pay at least $20 in the US for a cheap USB enclosure to hold and continue testing the old internal, so you may just want to replace the HDD and move on.

You say it's a "Macbook Pro 2012." Open System Profiler (Apple menu > About this Mac > More Info . . . ). What's the Model Identifier? It will be something along the lines of "MacBookPro9,1." Based on the fact that it has a HDD rather than an SSD, I'm guessing you have the "mid 2012" MBP (HDD) rather than the "mid 2012" Retina MBP (SSD).

To replace or remove the HDD isn't difficult. Instructions and video here for 13" non-Retina mid 2012 MBP: https://www.ifixit.com/Guide/MacBook...lacement/10378. Here for the 15": https://www.ifixit.com/Guide/MacBook...lacement/10761.

Repairing anything when far from home often reminds me of the "square peg in round hole" scene from Apollo 13 as ground control tries to jury-rig a solution to fix the carbon dioxide scrubbers:

"We gotta find a way to make this [cube] fit into the hole for this [cylinder] using nothing but that [pile of items available on-board Apollo 13]."

http://www.youtube.com/watch?v=C2YZnTL596Q

Sorry - I don't understand why you are saying that there are "no error messages" when I see on your screen shot that it says "Can't repair ..." in red.

I have no idea why the (internal) drive would be busy.
But one thing to try is to make sure that Spotlight is not trying to index that drive.
Go into Spotlight preferences (after booting from the external drive) and make sure that the internal drive is excluded from Spotlight.
Or maybe disable Spotlight entirely - google for instructions on doing that.