Problem with Time Machine and external hard drive

Hi all - new to these forums, but hoping you can help.

I have an Iomega external hard drive that I have been using with Time Machine to back up my MacBook on a regular basis for quite some time. It is connected via Firewire.

Starting in January, Time Machine would run for a while during a scheduled back-up to the external hard drive and then crop up with a message: "Unable to complete backup. An error occurred while copying files to the backup volume."

Can't imagine why this would happen at this point, as I hadn't changed any settings or done a single thing differently than how it had always run for the year or so previous.

In any case, I ran Disk Utility and did a Repair Disk command on the drive. When it was complete, I shut down the computer for the night and disconnected it from the outlet.

The next day, I booted everything up. Not only was the problem not resolved, but now the external hard drive isn't showing up on my desktop, in Disk Utility, or in the Finder. My System Profiler shows that an Iomega device is connected via Firewire (as it is).

So - a two-fold question. (1) What do I need to do to get the MacBook to recognize the external hard drive again and (2) How can I repair Time Machine to continue the regularly scheduled back-ups?

My MacBook is running OS X 10.5.8 and is completely updated with all software updates. The Iomega model is HDD1H and the device is operating and powered on fine.

Thanks in advance for your advice!

If Disk Utility can't see the drive at all, and you're sure its actually turned on, I'd say you MAY have a drive failure there (which would be quite surprising). Best way to find out: try hooking it up to another Mac.

If you don't have access to another Mac, try mounting the disk using USB2 instead of FW.

If it's still not showing up, call Iomega.

Thanks for the advice... I tried connecting by USB and the drive appeared in my Disk Utility, but not in the Finder or desktop. When I select it in the Disk Utility, the mount option becomes grayed out, as do the Repair Disk and Repair Disk Permissions options. Am I making progress with this? Going to try Iomega, but any other suggestions are welcome!

FW working, kind of

Shut everything down, unplugged it, then re-started it, with the Iomega drive connected by FW again. Now the FW is somewhat working, similar to the USB: it's appearing in my disk utility line-up, but cannot be repaired or mounted. Not showing up in Finder or desktop.

I was using this as a back-up via Time Machine, so if I need to just wipe it clear and start from scratch I'm fine with that. Just don't know how to go about it...

You can't wipe it clean if it's not being "seen". That drive is more than likely dead - failed. Do as chas_m suggested and give iOmega a call and ask for a RMA (that is if the drive is still covered under warranty). If the drive is not covered under warranty there's not much you can do except purchase a new one.

OWC has a good selection of FW 800 drives that you can choose from to replace the iOmega.

Regards.