Unable to mount Time Machine partition I have a WD external HDD which is plugged into my MacBook Air more or less all the time; it has two partitions one of which is my Time Machine disk. Just today I noticed that the hard drive is not mounting correctly anymore


On boot-up, both partitions do not show up in the Finder at all
When I unplug the drive and replug it back in, only the non-Time Machine partition shows up in Finder. It appears to work like normal i.e. reading and writing (I've already copied all my data off it)
I can't seem to either eject the disk or unmount the partition that is mountable. If I hit the eject button in Finder, the partition name greys out and is not clickable but does not go away.


Via Disk Utility, I am unable to either mount the Time Machine partition (I get the generic not able to mount partition error message) and I am also unable to run Repair disk on it (error message: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.). Screenshot below. I tried erasing the disk but that also did not work (error message: Couldn’t unmount disk.)



It sounds like my hard drive has failed (or is in the process of failing) - the only things that I makes me second guess myself and make me wonder if the disk is salvageable are:


The non-Time Machine partition appears to mount correctly and can be used as usual (although as mentioned above it cannot be unmounted)
The drive is not that old all: probably about 18 months old. I have drives that are older that are still ticking along nicely.


Is this a simple case of a failed drive (perhaps a defective product) or is this a symptom of a software related problem (e.g. there have been several instances where the drive has been unplugged without being ejected correctly)?
I had the same problem and resolved it like this.


Unplugged the drive
Turned off Time Machine in Pref
Rebooted the Mac
Plugged the drive back in
The Time Machine partition mounted