Cannot format external harddrive

To start: all applications on my computer work just fine when the hard drive in question is not attached to the computer. There are no other problems (that I know of).

I have an external 1.5 TB hard drive by Seagate. I called it "THE PIT". When I attach it to the computer via Firewire, and I try to access the data on it via finder, finder crashes. When I try executing the command "ls /Volumes", I can see "THE PIT" as one of the volumes. When I try executing "ls/Volumes/'THE PIT'", finder crashes.

When I try to open DiskUtility, it also crashes.

I gave up, and just wanted to remove everything. I used diskutil to profile the disk, and here is what I have:

$ diskutil info /dev/disk1
Device Identifier: disk1
Device Node: /dev/disk1
Part Of Whole: disk1
Device / Media Name: Seagate

Volume Name:
Escaped with Unicode:

Mounted: No

File System: None

Partition Type: GUID_partition_scheme
Bootable: Not bootable
Media Type: Generic
Protocol: FireWire
SMART Status: Not Supported

Total Size: 1.5 TB (1500301910016 Bytes) (exactly 2930277168 512-Byte-Blocks)
Volume Free Space: Not Applicable

Read-Only Media: No
Read-Only Volume: Not applicable (no filesystem)
Ejectable: Yes

Whole: Yes
Internal: No
OS 9 Drivers: No
Low Level Format: Not Supported

I then ran

$ diskutil eraseDisk free %noformat% /dev/disk1
Started erase on disk1
Unmounting disk
[ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ]

This dialog persisted for several hours before I closed it. So I ran

$ diskutil unmountDisk force /dev/disk1
Forced unmount of disk1 failed: at least one volume could not be unmounted

I do not understand what the problem is. Why can't I unmount the disk? Why can't I format it?

[Sumleilmus]

To help us help you, tell us:

What is your machine? Apple brand? "Hackintosh?"

What version of OS X is it running?

Have you ever successfully connected it to any FW800 device of any kind without crashing the Finder?

Has the external drive ever successfully connected to any other computer without crashing the Finder (or Windows Explorer, or whatever)?

If the Seagate external offers USB connectivity, what happens if you attempt to connect it via USB?

Does the external drive rely on bus power, or has it its own power supply?

[anthlover]

Ekk. Stop..... while we wait for more info from you. Use USB. Use USB. Firewire is great but NON oxford chip sets can be a big problem with crashing and reliability. Macsales sells drives and cases with Oxford. Not too many others. Seagate, Lacie, etc offer firewire but they do not indicate who makes their bridge boards.

It is possible the drive is bad.

*** Boot off your System DVD, ekk if its not Lion or Restore partition if it is Lion, and using the usb connection erase the drive in question. The bad drive can take your internal drive down with it durring crashes if you do the work booted of your internal.

[trevor]

All good advice above, I'll just add one small thing--try a different FireWire cable as well. When things get flaky and crashy, it's often a hardware problem of some kind. The most common hardware problem is a bad cable.

Trevor

[anthlover]

Agreed but better to skip the firewire for now or at least test /trouble shoot of boot dvd. And of course you can have a bad usb cable too. Happened to me just the other day.