External hard drive giving "Couldn't unmount disk -69888" error when reformatting...

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I'm trying to reformat an external hard drive that I had used on my old Mac mini that I no longer own; using my new Mac Mini, I can get it to show up on the desktop sometimes, but it won't let me write or reformat it; I get this "Unmounting disk: Couldn't unmount disk (-69888)" error.

Back in the day, I'd use Norton Utilities and figure all of this out, however since OS X I haven't done much troubleshooting of anything because Macs just... work. But now I'm having problems and the only program I have to try and wipe this drive clean (going to use as a Time Machine backup) is Apple's Disk Utility. That's not cutting it.

Any ideas on how I can get this external hard drive erased so that I can use it as a time machine backup?

Thanks

Randy
 

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chscag

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Welcome to our forums.

The error you're receiving is likely due to failing hardware. Especially if the drive does not always show up on your desktop when you attach it. I strongly recommend not using it for backing up or anything else. You have to be able to rely on your backups otherwise they're worthless.

Replace the drive with a new one. It's not like external drives are expensive nowadays. You mentioned Norton Utilities. Back when that was popular, drives especially large ones, were expensive. Times have changed. ;)
 

IWT


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Absolutely agree. The External Hard Drive (EHD) is finished and even if you ever got it working, never use it for Time Machine or other backups.

I know all that was said above. This is for emphasis:)

Ian
 
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Welcome to the forum. As you have been told, the drive is dead/dying. This is just to add one more vote for that determination.
 
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Thanks a lot! You've saved me a lot of time in troubleshooting. I'm a bit gun-shy about external hard drives right now because I (here's a story) watched the ads for weeks, then went to OfficeMax/Depot and purchased two Western Digital 10TB hard drives. I do this every year-and-a-half to two years, and the previous drives go into secure storage. So one backup and one redundant backup. I've never had a problem before.

(It's July 14th or so)

So, I had to go to two different stores because no single store had two of these drives. That's okay. I get home, and neither works. One can be seen with the Western Digital software tools, but in reformatting it, the drive just stalls for hours.

I tried a different computer, different cables, power supplies, safe start, etc. as this isn't my first rodeo with this kind of thing.

I contact Western Digital, they tell me to send them back for replacements.

So, I take the time and effort to box them up very well, drive to the post office and pay forty bucks to send them away.

Two weeks go by, there's no update on the RMA page even though USPS had confirmed delivery.

I get an email telling me they've been tampered with (modified, something like that) and that I will be receiving no replacements, nothing. They didn't even specify exactly what was wrong with them.

So, I've had a phone call with support, and a chat with online support who told me to email the department who told me that they weren't going to replace them. That was bumped up to a Level 2 Technician, and nothing happened with this for about ten more days. I finally emailed them again (polite) explaining this all again, and asked for at least a timetable on an answer, and was told to expect one this past Monday. Of course, there's nothing new on the status according to the support page.

What I did wrong? I didn't buy the warranties. I didn't do this because my dad used to sell them and he knew how often they were actually used, that it isn't worth the money's and the fact that so many past drives always work... so I didn't buy the warranty, where I could have just taken them back to the store.

Other than that, I don't see where I went wrong. I did as their tech department instructed, sent them back for replacements. They just kept them and didn't specify exactly why, just generally that they had been tampered or altered. Kind of hard to do when they don't even show up on my desktop.

What do you guys think?

Randy

Welcome to our forums.

The error you're receiving is likely due to failing hardware. Especially if the drive does not always show up on your desktop when you attach it. I strongly recommend not using it for backing up or anything else. You have to be able to rely on your backups otherwise they're worthless.

Replace the drive with a new one. It's not like external drives are expensive nowadays. You mentioned Norton Utilities. Back when that was popular, drives especially large ones, were expensive. Times have changed. ;)
 
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When using Disk Utility, there is a confirmation step that should be taken first. Look in Disk Utility > View, and confirm "Show all Devices" has been enabled.
 

chscag

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I've also had a bad experience with WD. Several years ago I sent a WD drive back to them as RMA. They replaced the drive but the replacement they sent only lasted for 2 days before it too failed. I tossed it in the garbage and will never buy another WD drive.
 
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Wow. I'm not surprised. If I don't get anything back, of course I'm not going to buy another one, ever. But even if things work out, I'm not going to do that again, and if I did I'm getting the warranty. The stress alone is nuts, as I don't have a job right now and it was risky buying them in the first place, but I can't let 30+ years of work go unprotected (although a lot would be on the older backups, but we all know how important backups are).

The sad thing is that if you'd asked me before July 14th, when I bought them, I'd have told you I've never had a problem with their drives.

I've also had a bad experience with WD. Several years ago I sent a WD drive back to them as RMA. They replaced the drive but the replacement they sent only lasted for 2 days before it too failed. I tossed it in the garbage and will never buy another WD drive.
I've also had a bad experience with WD. Several years ago I sent a WD drive back to them as RMA. They replaced the drive but the replacement they sent only lasted for 2 days before it too failed. I tossed it in the garbage and will never buy another WD drive.
 
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Try ‘diskutil unmountdisk diskX’ (substitute the X with the disk number). If that does not work, try ‘diskutil unmountdisk force diskX’.

Then retry the erasedisk command.
 

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