Hello everyone.
So I'm having some problems with my 27" iMac. It keeps cutting out like someone's pulled the plug. It's been to Apple numerous times, and has been mostly replaced by this point - new logic board, new screen, new hard drive, new power supply unit, everything but the case pretty much - but the issue still happens.
Last week on one of its tantrums, it took out my external Time Machine backup drive, which now won't mount at all. I can see it listed as a drive on System Information, however, so I tried to take a look using Disk Utility. I can't. If the drive is connected, Disk Utility sits at 'Loading disks' and won't do anything. If I unplug the external drive, it pulls up info about my internal drive immediately. I've plugged the drive into my laptop, and the same thing happens.
Every answered guide online just suggests rebooting the machine. I've tried this multiple times, especially if you include the unexpected shutdowns.
So, I think, let's take a look using the command line. Using 'distil list' the drive shows up, so let's try forcing it to mount.
Robs-MacBook-Air:~ Rob$ diskutil mount /dev/disk2s2
Volume on disk2s2 timed out waiting to mount
Nope. Can't mount. Then I try repairing the disk from Terminal.
Robs-MacBook-Air:~ Rob$ diskutil repairvolume /dev/disk2s2
Started file system repair on disk2s2 LaCie
Repairing file system
File system check exit code is 8
Updating boot support partitions for the volume as required
Error: -69845: File system verify or repair failed
Underlying error: 8: POSIX reports: Exec format error
Looking bad, right? At this point I figure oh well, it's only a backup drive, I might as well reformat it, it's only a backup drive anyway and I need to make sure I've got an up-to-date backup of my iMac before I take it back in to Apple.
Robs-MacBook-Air:~ Rob$ diskutil eraseDisk JHFS+ LaCie disk2
Started erase on disk2
Unmounting disk
Error: -69888: Couldn't unmount disk
Ah right. And so we come to where we are: I can't even format the disk because I can't mount it in order to unmount it. Which seems a bit silly when you think about it.
Where do I go from here? I'm happy to wipe the disk over and start afresh, less happy to can the disk entirely as it's a 3TB external drive. Is there a way of running the disk format process without the unmount step? Or how else can I get myself to a point where I at least have a fresh, blank drive?
Thanks in advance.
