OS X Mavericks doesn't read my external hard drive

This is what the Get Info window looks like on one of my external data drives:

It's a long shot, but try clicking the lock on the bottom and checking the "ignore ownership on this volume" box in the lower left corner.

I think most problems started appearing when the EFI changed from 32 bit to 64 bit. I've never, myself, had a USB or Firewire drive fail except on Mavericks where it did some weird stuff until I disabled drive sleep, but then again I take it right out of the box, skip any drivers, and put it to work.

The two rules of thumb I use with external drives are:

1. Don't mix Dos/Windows and Mac
2. Don't use external drivers

The latter is more important because it means you're relying on the company that developed the drivers to keep them up to date and they often don't.

- "ignore ownership on this volume" is greyed out and not selectable

You have to click the lock and enter your password first.

Amnesiac is not a good name for a hard drive. 😁

Drive Genius isn’t all that useful but it does have a surface scan function. Try running that on the drive. It’ll take a while, but the results will be informative.

Do you have access to another HD case? It would be interesting to take the drive mechanism out of its current enclosure and try to eliminate that as a cause. Or something like this would be massively helpful.

I know it's been asked if you installed drivers for the software and the response was "No." How about other software like anti-virus software or "cleaning" tools like MacKeeper etc. (Side Note: Let's please not turn this into another MacKeeper fiasco).

In any case tools like MacKeeper can do odd things to your system like delete critical files. Anti-virus software will often see anything it doesn't understand as an intruder and prevent access to the drive.

Normally if a volume can't unmount it would be because the system or a user is using something on that drive. Assuming this isn't the case, anti-virus software may be stopping Drive Genius from unmounting the volume.

...of course you would have to have something like that installed for it to be a problem.

If it was me I'd return the drive. One of the problems I've seen cropping up with external drives is they seem to be too reliant on firmware updates and drivers. For example, the Western Digital "MyBook" series won't even actually function at 100% unless you update both the firmware and their drivers. If their drivers aren't installed, then the power switch won't work and the volume space indicator lights stay at the bottom, even though the drive might be 80% full. Their drivers, when Mavericks came out, were actually outdated and the system would delete files because they don't keep stuff up to date. When I contacted WD about this problem they told me they had no support for Mac's, only Windows, and yet they advertise this as a Mac product.

From now on I'll just build my own external unit by buying a raw HD and then putting it into a simple, no frills case. I have some old FireWire and USB external housings like that, and I have no problems with them with any version of MacOS, including Mavericks.

At least you know it was a compatibiltiy problem.

Ciao

We had a similar problem with an external WD., We use a product named Scannerz to test the our drives (http://scsc-online.com/Scannerz.html) and on having problems with a drive we called their tech support and they told us they were seeing a lot of this on Mavericks.... well, maybe not a lot, but I gather it seems to be a higher than normal percentage. I asked them if they could elaborate on whether it was a USB, FireWire, or Thunderbolt specific problem and they indicated they hadn't heard any reports about problelms like this with FireWire or Thunderbolt, but pointed out that these days USB drives probably outnumber other types by more than 10:1 ratio.

It's rather odd, because if someone says they're having some type of a problem with something in Mavericks, others not having the problems act like they're in an utter state of disbelief.

A big part of the problem is that the majority of people doing the complaining, A) don’t have a bootable backup, B) don’t have the tools to properly diagnose the problem, and C) never wanted to spend the money on drives or utilities to backup, diagnose and repair their drive, but just want it fixed.

Every time new OS comes out. some people complain that their drives are no longer recognized. I suspect that this is because they upgraded without doing the requisite maintenance on their drive prior to the upgrade and without a bootable backup in case of a failure.