Hello, external harddrive? Can you hear me now?
April 25, 2009 3:53 PM   Subscribe

How can I get my mac to recognize my external hard drive again?

Disclaimer: I'm pretty new to macs, but would consider myself a competent user.

I have an WD 500gig My Book external hard drive that I use on both my macbook pro (running Mac OS X 10.4.11) and PC. I don't remember ever formatting it, it just worked on both as soon as I plugged it in.

A few days back, the hard drive accidentally unplugged from my mac (aka, I did not eject it). When I plugged it back in, the hard drive would not pop up on the desktop. I'm 99.9% sure that all the hardware is fine-- it still works on the PC, and lights and spins when I plug it in-- and when I go into the System Profiler, the USB says that my external hard drive is attached. (One forum said you can click and force it to manually mount the drive, but I can't figure out how to do that.) I also installed Disk Warrior, which recognizes the hard drive, but says "The directory cannot be rebuilt, the file system is unsupported." There are bullets under that that say " This disk is not a Macintosh disk; This disk does not appear on the desktop; This disk is 465.75GB in size."

Every similar problem I've read about (including this one) turns out to be either hardware or fixable by Disk Warrior. Please help!
posted by veryhappyheidi to Technology (16 answers total) 5 users marked this as a favorite
I had this problem on my Intel Mac Mini, I had to reboot the mac.
posted by dunkadunc at 4:10 PM on April 25, 2009

Yeah, seconding a re-boot before any further investigation.
posted by stumpyolegmcnoleg at 4:15 PM on April 25, 2009

Response by poster: Sorry, should have said: this was about a week ago. I've rebooted with the drive plugged in, not plugged in, different ports, etc. Nothing.
posted by veryhappyheidi at 4:16 PM on April 25, 2009

Just to elaborate, your drive was almost certainly pre-formatted as FAT32 which meant you could switch no problem between Mac and PC..unless you have re-formatted as NTFS or a Mac format such as HFS+, it should still be FAT32 and switchable.... Just try re-booting with the drive plugged in and Im sure OSX will recognize it again.
posted by stumpyolegmcnoleg at 4:18 PM on April 25, 2009

I had this problem with a WD MyBook 500g drive on a MBP on 10.4.11 from disconnecting it without ejecting it. What ultimately solved it was leaving the drive attached for a long period of time, something like 2-3 hours so it can rebuild whatever got screwed up. Make sure you don't let the machine go to sleep automatically. It has worked fine since then. YMMV, though, as always.
posted by knowles at 4:18 PM on April 25, 2009

Sorry, my bad timing heehehehe
posted by stumpyolegmcnoleg at 4:18 PM on April 25, 2009

Another try, seconding what knowles said, sort of. My Freecom external drive sometimes disconnects 'illegally' when iTunes opens (no I have no idea why...). When I re-plug it in it wont show up in the finder until its re-catalogued everything on the disc, something I can tell is happening by the led on the front of my drive flickering. This can take a while (its only an 80Gb drive). If you have a lot of stuff on your 500Gb drive it could just take a long while, several hours for OSX to finish scanning the disc contents and then when satisfied finally poppinh up an icon in the finder..Good luck.
posted by stumpyolegmcnoleg at 4:22 PM on April 25, 2009

Response by poster: Thanks for the suggestions so far! Unfortunately, I'm pretty sure that it's been plugged in for long enough periods of time, but I'm going to try that again. Also, the led is steady; no flickering.
posted by veryhappyheidi at 4:26 PM on April 25, 2009

Response by poster: Correction: the led was steady for about 10 minutes and then started blinking with about 5 seconds between each light-up. It wasn't doing this before...
posted by veryhappyheidi at 4:33 PM on April 25, 2009

I've had similar problems with my MacBook & multiple USB drives. There are two possibilities, one good & one bad. If you're lucky the problem is that the mount point just has some folders & files written over it. To clear them out (with the drive disconnected) open up a terminal window & type the following:
cd /Volumes
You should get back a listing of all mounted drives; one for the internal hard drive & one for each connected external disk. If your external drive is disconnected but there's still an entry for it you need to delete that entry with the following command:
sudo rm -rf "drivename"
substituting the name of the disk for drivename. Make sure you don't type the name of your system drive or you'll wipe your whole computer clean. You'll be prompted for the admin password; enter it & hit return. Close the terminal window & plug the disk in, it should automount & you're all fixed.
If you're unlucky the drive is corrupted & you need to do a recovery on it. As others have pointed out your drive is probably formatted as FAT32. There are programs that recover FAT32 drives under OSX; Disk Warrior is not one of them. TestDisk & Drive Genius 2 are two that I know of that can handle FAT32, although I believe Drive Genius at least needs an extra disk to dump your files to.
Good luck.
posted by scalefree at 5:01 PM on April 25, 2009

What does Disk Utility say about it? ( /Applications/Utilities/Disk Utility )

That's where you'll find the "mount" button, if it'll do any good. I'd be curious to hear if it recognizes it at least, & whether it recognizes the volume(s) on it. You ma have tried this long since -- I'm just bringing it up since you didn't mention it, yet.
posted by Devils Rancher at 6:19 PM on April 25, 2009

Response by poster: Thanks Devils Rancher-- I'm new to macs and didn't know to do this. Disk Utility has it showing up, but nothing happens when I click mount. I'm going to try repairing now.
posted by veryhappyheidi at 7:05 PM on April 25, 2009

I've had this happen a couple of times. First time, it was the mountpoint problem that scalefree mentions.

Second time, it appeared to be a due to differences between the primary & secondary FAT on the disk. Turns out Windows doesn't give much of a damn about whether the secondary copy on the disk matches the first but OS X does, and sits there silently hoping that through magic they'll eventually match. The solution was to plug it into a PC & do a disk check + fix errors.

To be honest, I've never had much success with DiskWarrior when all the other normal disk troubleshooting methods have failed...
posted by Pinback at 7:10 PM on April 25, 2009

Response by poster: Got an error: Disk Utility stopped repairing because the following error was encountered: the underlying task reported failure on exit.
posted by veryhappyheidi at 7:11 PM on April 25, 2009

Try this:
Disk Utility-->Erase-Mac OS Extended (Journaled)-Security Options-"Zero Out Data"
posted by Finder at 6:51 AM on April 26, 2009

Yeah, if the data on the drive is important, copy in to a PC for safe-keeping, then re-format the drive from the Mac. If the data is not important (if it's just a backup) then just reformat it HFS+ (Journaled). Since the advent of journaling in OS 10.3, the file system has been pretty robust -- journaling basically is the OS telling itself what it's about to do, and what it just did when writing files to disk, in case of a screw-up, like a power failure, or a corrupt file. I've had much less need for DiskWarrior since that point, but that way, DW and Disk Utility will be able to repair any future directory problems should they crop up, and it's not hardware-related.

Another good program to keep around if you've got mission-critical data that's worth money is Data Rescue II. I have only needed it once, (had a physically failing drive, did the freezer trick, and since I figured I had one pass at it at best, used DR II to grab the most important user files) but it did the trick. I think it can scour for files on drives with totally borked directories.
posted by Devils Rancher at 7:22 AM on April 26, 2009

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