External HD failure, think it's an unusual OS problem

(as I explain below, I think I've ruled out hardware as the cause for this problem, so that's why I'm putting it in the OS board)

Hi all,

This morning, my two year old trusty Time Machine external HD (Western Digital Caviar 750GB, Model: WD7500AACS) didn't show up when I booted up my Macbook Pro. The drive doesn't show up in finder, and isn't visible in the Disk Utility. This has happened before, and it's always been a problem with the firewire connection. My enclosure is a Sata dual drive firewire case just like this one.

So I did what I've done before, tried changing the connection from firewire 800 to firewire 400, to USB 2.0. In the past, when there's been a problem with one of the above, another connection standard seemed to work for some reason. But not this time.

I tried the other USB 2.0 port on my Macbook Pro, but no love there.
So I opened up the case and, after cleaning out some dust, since this is a dual drive enclosure and I'm just using the one drive, tried the other sata port, and even the other sata cable to rule those out as possibilities, but still no luck. And there doesn't appear to be an unusual noises coming form the drive; it sounds as if the internal parts are working normally.

Funny thing is, Windows can see the drive! I tried turning on the drive when running Windows XP under VMware Fusion, and sure enough, VMware detected the drive. Windows can't read it of course, since it's formated for Mac, but I can see the drive in the disk manager.

So this tells me there's nothing wrong with the drive or the enclosure, or the cable. Could this somehow be an OS problem. Don't understand why it just started happening.

Thanks!

Since Windows can "see" the drive we have to assume the electronics are OK.

See if this might be the problem. The article refers to Tiger and internal drives but it is likewise applicable for Leopard, Snow Leopard, and external drives.

Several folks have run into this before and the above fixed it.

Let us know.

Regards.

Well, the 'vanishing drive' fix didn't seem to do any good. First, I'm not sure this was my problem, as I couldn't see the drive in OS X even with 'invisibles' turned on (this is pretty simple with Path Finder); the drive truely wasn't being read (Time Machine didn't see it and wasn't running backups). Running the script suggested resulted in an error, which I was going to investigate, and maybe try the terminal solution when...

Good news: I left the drive connected while I went to get some lunch, and when I came back an hour later, the problem had fixed itself, and Time Machine was backing up my startup drive. So, problem solved, for now.