Can't Unmount Hard Drive For Repair Mac
Normally when you plug in an external hard drive to your Mac's USB port you will see it mount on the desktop. You can also see it in the Finder in the left-hand column under Devices. Seems to me all this is related to the internal drive, even though some FW drives can mount/unmount without problem. All external FW drives have been checked and/or fixed with another computer (G4/OSX10.3.9) and function perfectly with it. 
To boot from another hard drive or a USB flash device, hold down the option key and start up your Mac. The Mac OS startup manager will appear, allowing you to select the device to boot from. The Mac OS startup manager will appear, allowing you to select the device to boot from.
I have a Western Digital 500gb external hard drive, with 2 partitions, 'KAINARC' and 'JUNGLEMAC', connected to my Intelmac (Tiger 10.4.11 via my firewire, i have connected via usb but the problem is still the same). I may have shut down the drive improperly to cause this situation. KAINARC now appears on my desktop, but the partition of JUNGLEMAC does not.
I go to disk utility and both partitions are visable, KAINARC is mounted but JUNGLEMAC is not. I cannot mount JUNGLEMAC. When i try to verify and repair the partition I get the message: Verify and Repair disk JUNGLEMAC Error: The underlying task reported failure on exit 1 non HFS volume checked 1 volume could not be repaired because of an error So I try to verify and repair the partition KAINARC but get this message: Verify and Repair disk KAINARC Repairing disk failed with error Could not unmount disk So I have opened diskwarrior (unbelievably long time to start up and scan disks) in the hope of fixing the hard drive, but when i try to repair I get the error message 'unable to unmount KAINARC'. I have tried other repair/recover programs but get the same message: 'Could not unmount disk KAINARC' Im asuming that to fix the hard drive it has to be able to unmount KAINARC. Does anyone have any ideas of how I can fix this problem. I would normally reformat but I have a lot of stuff on the hard drive that I dont wont to lose.
You tube how to back up computer on external harddrive for mac. It's called which supports you to simply or other storage devices with just 3 simple steps.
I've had the same problem, and ended up having to use Disk Warrior to recover the files onto another drive, toast the uncooperative drive, reformat, and move the recovered files back to the reformatted drive. It's not fast - even on Firewire. I let it run overnight for a 60GB drive. DW will let you set up a logical disk on the desktop to inspect the recovered files before toasting the bad drive. You should see the entire folder structure, except the possibility of a few corrupted files. If you don't like the way it looks, abort and try again.
Hard Drive Won't Mount Mac
Can Unmount Hard Drive For Repair Mac
Of course you need a drive as large as the files you want to recover, since it ddoesn't do any compression. It's a recovery tool, not a backup. I don't know if youi can use the logical partition on the same drive. I'd see if DW has any info on this, but not take the chance it it doesn't. Drives are fairly cheap (.