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Old Jun 17, 2012, 3:06 PM   #1
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Default Problem with 1TB USB attached drive

I too am following this thread closely as one of my hard drives is having a similar issue. It's a 1TB WD USB drive and had two iPhoto libraries saved to it. I had a family member use my computer to access the internet they accidentally messed up the drive. It turns out they didn't have experience with OSX and somehow clicked too many things and now the drive isn't accessible. No odd sounds when plugged in and the white LED lights up when you plug it in.

Here's what I get:
"The disk you inserted was not readable by this computer" Initialize, ignore, or eject are the options I'm given at this point.

I haven't done a thing to it since this happened for fear of losing the data. One of the libraries is backed up, but the other relatively new one isn't and there are pictures from a trip that I would rather not lose. Any ideas?

Feel free to either move this or just let me know if I'm totally hijacking the thread...just figured that since it's the same subject it might be applicable.
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Old Jun 20, 2012, 7:33 PM   #2
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..."The disk you inserted was not readable by this computer" Initialize, ignore, or eject are the options I'm given at this point.

I haven't done a thing to it since this happened for fear of losing the data. One of the libraries is backed up, but the other relatively new one isn't and there are pictures from a trip that I would rather not lose. Any ideas?
Have you tried to access the disk with Apple's Disk Utility? It won't modify anything unless you tell it to.

After that, it depends on your definition of "would rather not lose." Either pay a pro data recovery outfit BIG bucks or try DIY. (And data recovery companies don't guarantee results!)

If you want to do it yourself, I had some success with Data Rescue II. Takes hours to scan the bad drive and extract everything it can but, in the end, we lost very little.

FYI, Disk Warrior and Drive Genius were of no help with a disk that wouldn't mount.

Craig
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Old Jun 21, 2012, 4:20 PM   #3
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thanks PvrFan - I'll give it a look.
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Old Jun 21, 2012, 4:45 PM   #4
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...I haven't done a thing to it since this happened for fear of losing the data...
That's a good thing (you didn't try to use any utilities to "fix" it).

Sorry, I didn't notice your posts earlier.

My advise... do *not* use any utilities that write to the drive in any way to try and "fix* it before you get a good disk image copy of it.

IOW, there are a number of ways to make a sector by sector copy of the drive and save it to a disk image file. That way, if any utility you try to use to fix the file system problems causes more damage (which is likely if it has physical issues), you'll still have a copy of the drive, just the way it is right now. That way (if the drive does have physical problems), you can move the disk image back to a good drive and run file system utilities to fix the file system, without them needing to worry about "hard errors" (since a new drive wouldn't have physical problems).

Chances are, it's just a corrupted file system. But, i'd play it very safe if the data is important to you, as I've seen the ability to recover data totally destroyed trying to use utilities designed to fix file systems (chkdsk, fsck, etc.).

How is this drive formatted (FAT32, NTFS, HFS+)?

Do you have another drive with as much free space on it as the size of the original drive (1TB from what you said)?

If you've got another drive with 1TB of free space on it (and you need 1TB, the size of the original drive, not the space used on it), I can try to talk you through making a disk image copy of the drive using specialized utilities that can work around physical errors before you attempt to use any utilities to fix the file system (as sometimes that can destroy the ability to recover your data if the drive has physical errors and it continues to degrade while utilities are trying to map out bad sectors).

Let me know more about it (how it's formatted, if you have 1TB free space on another drive) and we can go from there.
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Old Jun 21, 2012, 4:57 PM   #5
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P.S.

In the meantime, I've now moved the posts related to your issue to this new thread (so that it will be separated from the problems someone else was having, as not to confuse readers).

But, give us some more info first (for example, how the drive is formatted, if you have 1TB of free space on another drive)

Chances are, it's just a file system corruption issue. But, it could also be a failing component in the enclosure, failing drive with physical errors, etc. So, I'd suggest we get a good disk image copy of it if possible as a first step before proceeding (which will require 1TB of free space on another drive).
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Old Jun 21, 2012, 6:57 PM   #6
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It's the largest external drive I have so I'm unable to copy it over right now. I'm not against getting another so I can go that route, but want to make sure it's a necessary step before putting the money down on one.

I'm not certain of how it's been formatted. I just formatted however my Mac wanted me to when I first connected it. How can I tell at this point?
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Old Jun 21, 2012, 9:13 PM   #7
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Personally, I never try to repair a drive without making a disk image copy of it first. That way, if a repair utility causes problems, I always have a disk image of it exactly as it was to begin with.

So, what I'd do is get another drive as large or larger than the source drive, and make a disk image copy of it before doing anything. Or, if you have 1TB of free space on your internal drive, you could store the disk image there (it doesn't have to be a dedicated drive).

The utility I use for that purpose (making a sector by sector copy of a drive) is GNU ddrescue (and I also see where some sites have precompiled binaries for OS X available).

I'm not an OS X user. But, some of the utilities I use with Linux are also available for OS X. That would save you the trouble of downloading a Linux Live CD and booting into it to use those types of utilities (just download binaries already compiled for OS X). What version of OS X are you using now?

To see how the disk is recognized in OS X, you can plug it in and type this from a terminal (cmd prompt):

diskutil list

Note that if you see the same errors, do *not* select Initialize (as that will format the drive). Select Ignore instead.

That command should give us the device names for your drives and partitions and how they're formatted. Just paste the results into this thread.

With OS X, there's a Disk Utility program you can use to try and repair drives. But, I suspect you'd have better luck with fsck or fsck_hfs from comments I see about the Disk Utility program in OS X. You may also find that the fsck utlities in Linux work better (as Linux can handle HFS+ file systems with the right drivers installed) by booting into a Linux Live CD and running them.

But, we'd need to know what file system it's using to get a better idea of what utilities may work best. Chances are, it's HFS+ (what Apple calls OS X Extended) with a Mac. Whether or not it's got journaling enabled is a question I'd have, as some utilities may work better than others if it is setup that way.

Again, see what this tells you with it plugged in (paste the results into this thread):

diskutil list

But, personally, I would not attempt to fix the file system using utilities without making a sector by sector copy of the drive first. That would also tell you if the drive has any physical errors on it (sector read errors), since utilities like ddrescue report when they see them.

It's a very smart utility when you use a log file with it, as it can keep track of what it copied OK and make multiple passes, only attempting to copy areas it hasn't already copied OK during subsequent passes. That also lets you do things like let the drive cool off between passes, as a failing drive usually works better when it's cooler.

It may not have any physical problems. But, making a disk image copy using that type of utility would let us know that, and we'd have a good copy of it before attempting to "fix it" (which could cause a lot of issues if the drive is failing with sectors continuing to go bad while a utility is trying to fix file system problems). I've seen that happen before with failing drives, which is why I would never attempt to fix a drive without a good sector by sector copy of it first if the data is important.

If it didn't have errors, then we could try using file system utilities to fix it. If it did have a lot of errors, we'd know that it's probably a better bet to replace the drive, write the disk image back to a new drive, then run file system utilities on the new drive (since it wouldn't have any physical errors, and the file system utilities would only need to deal with file system problems instead). You could also mount the disk image as a loop device and try to fix the image file. But, with only one good copy, I'd get another drive to do that on if the original did have any errors.

Or, just get another drive to begin with and use ddrescue to clone it (and it can make multiple passes against the source drive if it does have errors, writing to a destination drive), instead of making a disk image copy to a file. You can use it either way. Then, just run file system utilities (fsck or fsck_hfs, and what works best and what parameters are needed would depend on the file system type and if it's journaled or not).

There are many ways to approach it. But, personally, I would not touch the drive with any utilities that write to it before making a disk image copy of it (or just cloning it to a new drive instead)

How about your internal drive? Does it have 1TB of free space on it? If so, could use it to store a disk image of the bad drive (a disk image is just like any other file, as it's just a file containing a sector by sector copy of the source drive). That way, you wouldn't need to buy another drive unless the source drive did have a lot of physical errors.

Instead, we could just run file system utilities on the bad drive. But, I wouldn't do that without a good copy, in case it is failing with physical errors.
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Old Jun 22, 2012, 7:25 AM   #8
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Also note that sometimes external drives have issues with the power adapters and enclosures, not the actual drive.

I'd make sure to try leaving the power adapter unplugged for a little while, too (so it cools off and may work better). Or, if you've got another one with the same voltage and current rating, try it instead. Ditto for trying a different USB port on your computer. If it's a circuit board problem in the enclosure, just removing the drive and using it in a different enclosure (or docking station) can solve that kind of issue. But, I'd see how it's being recognized first using the diskutil list command as mentioned above. Then, if it were mine, I'd try to make a sector by sector copy if it before doing anything else (and just making the copy using something like ddrescue can tell you things like if the drive is actually readable as a block device or not, so you'll know if you have other issues or if the file system is just corrupted).

Do you know exactly what the user did when it stopped working? Are you sure they didn't knock if off the desk or bump it hard while it was being written to? If so, then it's more likely the drive has physical issues (head alignment, damaged sectors, etc.).
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Old Jun 22, 2012, 1:01 PM   #9
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Quote:
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Personally, I never try to repair a drive without making a disk image copy of it first.
Good advice. When you are dealing with failing hadrware, you may only
get one shot at it.
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Old Jun 22, 2012, 5:47 PM   #10
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Wow - where do I start? Thanks JimC for all the info...I know that took some time to prepare and I really appreciate.

1 I don't have another 1TB drive and my laptop has only a 250gb drive so I may have to wait to try copying it directly to another drive.

2 I have the drive currently at work so will have to wait until next week to get it and try accessing to see how it's recognized.

3 It's a USB drive so I don't think the power adapter nor enclosure is the culprit. I had it resting on a shelf on my desk when I came upon my mother clicking away on the computer. She was visiting us out on the east coast and tried to check her email. Next thing I know she was at the point of initializing the drive. I think the Time Machine popped up on her and she was a little flustered and just started clicking anything that said Yes or Ok. As frustrated as I was, I just smiled, quickly grabbed the mouse, and told her it was okay (after also quickly disconnected the USB input). Hard to be too angry with your mother, you know?

4 I also spoke with the IT guys at work and when we reimage computers we just ghost the images to them. They seemed to think that I may be able to just ghost the drive to the server and see what we can access from there. What are your thoughts on that? If I'm leery over it at all I won't try it...but it was an idea that they brought up. All it does is mirror the drive so in theory it shouldn't affect what is currently on it.

Thanks again for all the information. I'm taking it slow on this as I'm not on a crunch to get it resolved ASAP...but still like to make progress.
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