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I have a new 4TB external drive. If the device is on, my mac will fail to boot (blank white screen) and when the drive is turned off, reboot immediately resumes. I cannot boot to safe mode, single user or verbose when the drive is on.

After boot and I turn on the drive, disk utility does not recognize the drive, but system profiler does see the HDD as an unknown device. After about 20 minutes Disk utility finally sees the drive

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *4.0 TB     disk2

Disk Utility (GUI) does not allow me to verify, repair or partition the disk and it appears as unformatted and read only.

OSX 10.6.6 - Drive IOMEGA UltraMAX Plus 4TB (2 bay stripe set) - Connected via firewire

If I cannot erase or partition the drive, what is my next step?

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Try running OSX off your install disk and using Disk Utility there, if that doesn't work use a linux livecd if you have one.

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Can you connect the drive via USB or via the network?

Can you connect the drive to another computer (Mac or PC) and use it?

Check for firmware updates to your Mac (they usually get installed by Software Update, but you might need to run them by hand from /Application/Utilities or download them from

Check for firmware updates to your drive. This is somewhat iffier, and might require a Windows machine to upload them to the hardware.

If the drive works via the same connection on a different machine, you might have a defective motherboard. If the drive doesn't work in any machine, it's probably defective (this is much more likely, actually).

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