Wiping an External Hard Drive

[FogCityMac]

*I apologize if this is not in the correct forum.*

I am wiping an external hard drive I used for backing up my MacBook Pro in Time Machine.

I am using Disk Utility to erase the hard drive. I selected the most secure setting which goes through seven passes.

The erase is currently in Pass 1. The status states, "Erasing "MBP Backup" [the external drive's name] and creating "MBP Backup"

What does "Erasing... and creating" mean? What is being created? Simply the newly overwritten drive?

Also, did I go overboard with 7 passes? Would one or two have been sufficient? The external hard drive is 1TB. How long will it take to erase it with 7 passes? Once the first pass is complete, do subsequent passes go by more quickly? If each pass is equally slow, can the process be stopped and started over to perform a pass or two? There is no cancel button. Can I simply unplug the hard drive if needed to stop and restart?

Thanks for your help.

 

[DeltaMac]

"erasing" and "creating" mean what you might expect... The volume is erased, then a new volume is created--same name.
You chose to erase the volume, with a multi-pass erase, ostensibly for a more secure result.
So, the Create process uses the same name as the erased drive.
The other choice is to change the name to something else, before you start the erase.
A better method would be to erase the device, not just the volume. That would remove ALL volumes on the device, ot just the volume that exists, and give you a result that has only the one volume, leaving the result named "Untitled". Again, you can simply enter a name for the new volume before you start the erase.
The multi-pass erase is a bit of over-kill, IMHO, as it usually leaves the user with a false sense of security (again, just my opinion), and if the drive is large, can take a l-o-n-g time. It writes zeroes to all available blocks, so each pass should take more or less equal time. Any mechanical problems can be magnified by the "write to all blocks" part.
Pull the plug on a hard drive during writes? Not the greatest idea in the world, but do it if that's your only choice, such as running out of time, and you have to take the Mac with you, etc.

 

[NoBoMac]

ADD: since mentioned this is a Time Machine drive, if you have enabled encryption on it, a simple re-format should be sufficient, especially if you used a strong password/encryption key for the drive. On re-format, the encryption key that was encrypted with the key you provided gets erased, making it pretty much impossible to recover anything.

 

[FogCityMac]

"erasing" and "creating" mean what you might expect... The volume is erased, then a new volume is created--same name.
You chose to erase the volume, with a multi-pass erase, ostensibly for a more secure result.
So, the Create process uses the same name as the erased drive.
The other choice is to change the name to something else, before you start the erase.
A better method would be to erase the device, not just the volume. That would remove ALL volumes on the device, ot just the volume that exists, and give you a result that has only the one volume, leaving the result named "Untitled". Again, you can simply enter a name for the new volume before you start the erase.
The multi-pass erase is a bit of over-kill, IMHO, as it usually leaves the user with a false sense of security (again, just my opinion), and if the drive is large, can take a l-o-n-g time. It writes zeroes to all available blocks, so each pass should take more or less equal time. Any mechanical problems can be magnified by the "write to all blocks" part.
Pull the plug on a hard drive during writes? Not the greatest idea in the world, but do it if that's your only choice, such as running out of time, and you have to take the Mac with you, etc.

Thanks for the helpful reply! Two questions.

Where is the option to "erase the device" (your better method)? I followed the instructions from an Apple Support doc but missed that somewhere.

If I really don't need 7 passes, ie, one or two are good enough, AND I don't plan to use this external hard drive again, any downside to "pulling the plug?"

Thanks for your help!

 

[DeltaMac]

You can erase the "device". With that drive attached to your Mac, Disk Utility open.
Your external drive will be in the list on the left.
Go to the View menu, and choose "Show All Devices"
You can choose the line above the line with your external drive volume name. That will also have manufacturer's identification in that line. THAT's your device--select that line, then erase will erase the device, not just the volume.

If you are not planning to use that external again, you COULD destroy it. A few passes with a power drill can do enough.
I would pry the case open, so you can put holes through the platters. Good fun, eh?

 

[FogCityMac]

You can erase the "device". With that drive attached to your Mac, Disk Utility open.
Your external drive will be in the list on the left.
Go to the View menu, and choose "Show All Devices"
You can choose the line above the line with your external drive volume name. That will also have manufacturer's identification in that line. THAT's your device--select that line, then erase will erase the device, not just the volume.

If you are not planning to use that external again, you COULD destroy it. A few passes with a power drill can do enough.
I would pry the case open, so you can put holes through the platters. Good fun, eh?

Awesome. Thanks.

 

[gilby101]

A few passes with a power drill can do enough.
I would pry the case open, so you can put holes through the platters. Good fun, eh?

Good fun - yes. But I would be very careful not to risk splinters in my eye.

Also, did I go overboard with 7 passes?

Almost certainly. Multiple passes were only added to satisfy the requirements of the military and spy agencies. It is possible to take the disk apart and (with lots of high tech gear) inspect the magnetic zones in detail with aim of recovering the erased data. One pass is enough for most of us. Easier is to always encrypt the drive, in which case you don't need to do any passes - but you do need to remember the password!!

 

[Fishrrman]

You are wasting your time (and the drive with "seven passes").

One "zero-out" pass would have been "all that was needed"...

 

[Basic75]

You are wasting your time (and the drive with "seven passes").

One "zero-out" pass would have been "all that was needed"...

Even a single pass is usually overkill. On an encrypted drive I would have simply dd'ed over the first couple of MBs with /dev/zero.