one 250 GB firewire hard drive shows up on desktop as two 250 GB harddrives...

Please post the specific model number and vendor for the drive enclosure; that'll lead to the specifications, and that can help determine whether this device is one 250 GB drive with something weird, two separate 250 drives, or two separate partitions on one single 500 GB drive, or something else entirely.

It would be good to know what unix is thinking about the situation.

Macintosh-HD -> Applications -> Utilities -> Terminal

type in diskutil list

# Press return to run a command.

mac $ diskutil list
/dev/disk0
   #:                   type name               size      identifier
   0: Apple_partition_scheme                    *74.5 GB  disk0
   1:    Apple_partition_map                    31.5 KB   disk0s1
   2:         Apple_Driver43                    28.0 KB   disk0s2
   3:         Apple_Driver43                    28.0 KB   disk0s3
   4:       Apple_Driver_ATA                    28.0 KB   disk0s4
   5:       Apple_Driver_ATA                    28.0 KB   disk0s5
   6:         Apple_FWDriver                    256.0 KB  disk0s6
   7:     Apple_Driver_IOKit                    256.0 KB  disk0s7
   8:          Apple_Patches                    256.0 KB  disk0s8
   9:        Apple_Bootstrap                    977.0 KB  disk0s9
  10:              Apple_HFS Classic            1.1 GB    disk0s10
  11:        Apple_UNIX_SVR2                    3.2 GB    disk0s11
  12:              Apple_HFS Macintosh-HD       69.9 GB   disk0s12
  13:        Apple_UNIX_SVR2                    177.4 MB  disk0s13
/dev/disk1
   #:                   type name               size      identifier
   0: Apple_partition_scheme                    *931.5 GB disk1
   1:    Apple_partition_map                    31.5 KB   disk1s1
   2:         Apple_Driver43                    28.0 KB   disk1s2
   3:         Apple_Driver43                    28.0 KB   disk1s3
   4:       Apple_Driver_ATA                    28.0 KB   disk1s4
   5:       Apple_Driver_ATA                    28.0 KB   disk1s5
   6:         Apple_FWDriver                    256.0 KB  disk1s6
   7:     Apple_Driver_IOKit                    256.0 KB  disk1s7
   8:          Apple_Patches                    256.0 KB  disk1s8
   9:              Apple_HFS ServiceRepairManuals 499.8 GB  disk1s10
  10:              Apple_HFS ext-80             79.8 GB   disk1s12
  11:              Apple_HFS Second-80          79.7 GB   disk1s14
  12:              Apple_HFS Ext-Remainder      271.8 GB  disk1s16
/dev/disk2
   #:                   type name               size      identifier
   0: FDisk_partition_scheme                    *7.5 GB   disk2
   1:              Apple_HFS Backup             7.5 GB    disk2s1
 mac $ 

Format a disk

Macintosh-HD -> Applications -> Utilities -> Disk Utility

Start up disk utility.
On the left pane view, you will see a list of all your disks. Click on the disk.
Click on the partition tab.

You will now see how your disk is currently set up. Fill in the information as appropriate. You should pick Mac OS Extended (Journaled).

Click on Options...

Select Apple Partition Map to boot a PPC.

More details on formatting.
http://www.kenstone.net/fcp_homepage/partitioning_tiger.html

OK, so this is home-grown hand-built stuff, and formatted by somebody else.

Are the two desktop icons identical, or does one have an arrow overlaid? (If so, that could be what's called a link; an alias.)

Also select with the cursor and then press ⌘I (or select Get Info from the alternate-click popup) on each of the two icons, and determine if the results identical, or if they differ.

Also rccharles' request, as well — that'll indicate whether there's a second disk or a second partition around somewhere else that's the same size, or something that's odd about the current device.

Looks to me if you have four disks of these sizes disk 1tb, 250.1gb, 250.1gb, 1tb, 320.1gb.

What do you think you have?

Could you put some data on one of the 250.1 disks and see if it appears on the other?

Do you have two 1tb disks?

I guess we should look at system profiler and try to figure out how the disks are connected to the system. I'll post another message about this.

You can post images.

-------------------------------

How to show us a screen image. Avoid personal identification.

command + shift + 3 Will take entire screen. You hear a click.

command + shift + 4 Lets you decide what to take. Mouse pointer changes. Move mouse to upper left corner of desire image. Hold down left mouse key where to start image. Drag mouse to lower left of where you want to stop image. Release mouse.

You will get a picture n.png file on the desktop.

On the forum input panel you will see the camera icon.

click on camera icon.

another window will appear.

Make sure you have selected the from your computer tab.

click on Browse button

An open file panel appears. Select the file.

After selection a file, I have this screen showing.

You will have to click on Insert Image. You may have to scroll down to see Insert Image button.

By chance, could you have both a usb and firewire connection to the device. You should have only one. Firewire is preferrable.

Robert

Shut down. Using just your (presumably) internal boot disk, disconnect everything else on the USB other than the problem drive — USB hubs and all — and boot.

The enclosure maybe bad. Detach the firewire cable and try usb. Reboot. See if you get one or two drives.

You could try resetting the firmware. These PPC computers where made before 2006.

Sometimes if volumes don't appear in Startup Manager (what you get when you hold down the Option key at startup), you need to reset the Mac's PRAM, NVRAM, and Open Firmware. Shut down the Mac, then power it up, and before the screen lights up, quickly hold down the Command, Option, P, and R keys, until the Mac has chimed twice more after the powerup chime.

Then, before the screen lights up, hold down Command-Option-O-F until the Open Firmware screen appears. Then enter these lines, pressing Return after each one:

reset-nvram

set-defaults

reset-all

"The reset-all command should restart your Mac. If so, you have successfully reset the Open Firmware settings."

http://support.apple.com/kb/TS1812?viewlocale=en_US

Should the fail...

Try taking the battery out for 10 minutes. Put battery back in. Cross fingers. Power the machine back on.

How to eject a cd from the internal cd drive:

eject cd

List of devices:

devalias

List of variables:

printenv

More than you ever wanted to know about open firmware

http://www.firmworks.com/QuickRef.html

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Did you say what computer you have this attached to? Could try another machine. Could try windows box.

Sometimes the supporting fireware hardware doesn't suppor the mac as well as windows.

I recommend you do a google search on any external harddrive you are looking at.

I bought a low cost external drive enclosure. When I started having trouble with it, I did a google search and found a lot of complaints about the drive enclosure. I ended up buying a new drive enclosure. On my second go around, I decided to buy a drive enclosure with a good history of working with Macs. The chip set seems to be the key ingredient for firewire support on mac computers made before 2006 . The Oxford line of chips seems to be good. I got the Oxford 911.

I've bought two external drive from OWC which I have not had problems with. The cheap ebay external drive gave up the ghost.

I'd give OWC a call. 1-815-338-8685.

Well the system seems to think that two drives of size 250.1 are attached.

/dev/disk1

/dev/disk2

This indicates two disks.

Partitions are this way:

disk1s1

The s indicates a partition. In this case partition 1 on disk1.

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *250.1 GB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_HFS Untitled 249.7 GB disk1s2

/dev/disk2

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *250.1 GB disk2

1: EFI EFI 209.7 MB disk2s1

2: Apple_HFS Untitled 249.7 GB disk2s2

I do not know why this is occuring.

There's no need for installing software to access a USB or FireWire disk on OS X, and I'd generally avoid installing add-on software as some of that has historically caused weird problems, and tends to add stuff you don't need, and may not want.