Problems Formatting External hard drive on MBP

I have a Seagate 1.5 TB external. I can no longer read data from it. I want to erase all data and reformat.

Conventional Efforts:
When I plug it in to my MBP (via Firewire 800), it shows up on the desktop as mounted. However, when I try to access the files on it via Finder, Finder crashes (beachball). I open disk utility, and I can see the disk. When I press erase, the dialog is stuck at "Unmounting Disk".

Why does this happen? What can I do to help debug the problem?

What happens if you unmount the disk before you go into DiskUtility ?
Could it be that the disk is being indexed by spotlight ?
Also, does the disk have another interface to try like USB ?

Cheers ... McBie

McBie said:

What happens if you unmount the disk before you go into DiskUtility ?
Could it be that the disk is being indexed by spotlight ?
Also, does the disk have another interface to try like USB ?

Cheers ... McBie

Click to expand...

Attempt in Terminal [Firewire 800]
Voldemort [~] $ diskutil unmountDisk /dev/disk1
Unmount of disk1 failed: at least one volume could not be unmounted

Attempt in Terminal [USB 2.0]

Voldemort [~] $ diskutil unmountDisk /dev/disk1
Unmount of all volumes on disk1 was successful

-- so the unmounting worked here


Voldemort [~] $ diskutil list /dev/disk1
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.5 TB disk1
1: EFI 209.7 MB disk1s1
2: Apple_HFS THE PIT 1.5 TB disk1s2


Voldemort [~] $ diskutil eraseDisk HFS %noformat% /dev/disk1
Started erase on disk1
Unmounting disk
Creating partition map
Error: 22: POSIX reports: Invalid argument

Voldemort [~] $ diskutil list /dev/disk1
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: *1.5 TB disk1

-- So the volume information is gone

Voldemort [~] $ diskutil eraseDisk HFS %noformat% /dev/disk1
Started erase on disk1
Unmounting disk
Creating partition map
Error: 22: POSIX reports: Invalid argument

-- but I still can't erase the disk

EDIT: Even though POSIX gives an error, I then formatted the disk with diskutil, and it seems to be working just fine...

Sorry mate, but all that technical terminal stuff .... I am afraid you have completely lost me.

Glad it worked out for you on USB ( if I understand this correctly )

Cheers ... McBie