Securely wiping external hard drives and SSD

[kat.hayes]

I have a bunch of old 3 and 4TB hard drives that I am going to get rid of, and I want to securely wipe them. I started securely wiping a 4TB drive late Thursday with the most secure settings and it is still going through the process as of right now on Monday morning.

1. Are the most secure wipe settings overkill for hard drives? What would it take for someone to recover my data using a lower secure wipe setting?
2. Is the process/speed of wiping the drive dependent on the speed of my Mac in any way?
3. What is the equivalent of securely wiping a SSD?

Thanks

 

[velocityg4]

I've done reading on this. When this was really an issue was when drives were a couple hundred MB maybe a couple GB. You could potentially glean some data without multiple secure wipes. After drives started hitting 10's of GB. Anything over a 3-pass wipe is generally overkill. With TB drives, even a professional data recovery lab wouldn't likely get anything off a drive that was simply zeroed out. They probably wouldn't even be willing to try if you told them you zeroed a drive.

Heck, I've tried pulling data off a drive where someone reformatted it accidentally. Then reinstalled Windows. Not even rezeroing the drive. Just a partial write filling maybe 20% of a 100/200GB drive (Windows, Updates, Software, Cache, Swap). Was enough to make everything I pulled from it garbage. Using the best data recovery software of the time and a low level scan. I only pulled maybe 2% usable data. The person was pissed that I charged so much. But I told them ahead of time. That since they already reinstalled Windows and had been using it for weeks. That data recovery was extremely unlikely and I'd only even be willing to try if they paid. I really did try to talk them out of it. Because I knew it would be a waste.

Now I can't guarantee zeroing is enough. I think it is. 3-pass seems way more than enough. But if your data is so valuable that someone would go to such herculean efforts (most likely failing). You should drill the drives and dunk them in a bucket of salt water.

 

[kat.hayes]

My data is not that important by any means. I do have photos, important documents like financial stuff, etc. After getting rid of the drives I will have no idea where they end up, that is why I have any concerns at all.

Any idea what would happen if I stopped the secure wipe process that my drive is currently going through right now? Could I simply reformat the drive afterwards to make it usable, assuming that the secure wipe has already done enough after 3 full days of wiping the drive? Could it cause damage by stopping the process? Thanks

 

[DeltaMac]

If you will "get rid of" those drives (recycling as junk), then it would be much simpler (and quicker) to physically damage the drives so they can't be used. Drill a few holes in the central part of the case,so holes go through the platters.
If you want to sell the drives, then of course, you do what you need to do to wipe the drives. Again, a quicker way would be to encrypt the drive, then wipe the encrypted partition. Not gonna retrieve anything without using something at an NSA level.

 

[Fishrrman]

Using disk utility, "one pass" with zeros is all you need for platter-based hard drives.

...Unless you're worried about the NSA getting into them. In that case, you have much more to be worried about. Better take a hammer to them.

Will disk utility even offer a "secure erase" option when erasing an SSD?
(don't think I've ever tried it).

I do know that old copies of Drive Genius WILL offer a "shred" option which [supposedly] secure erases even SSDs.

Having posted this, I don't think I've ever tossed out a hard drive that was still working. I'd find some use for it, somewhere...

 

[KaliYoni]

I have a bunch of old 3 and 4TB hard drives that I am going to get rid of, and I want to securely wipe them. I started securely wiping a 4TB drive late Thursday with the most secure settings and it is still going through the process as of right now on Monday morning.

1. Are the most secure wipe settings overkill for hard drives? What would it take for someone to recover my data using a lower secure wipe setting?
2. Is the process/speed of wiping the drive dependent on the speed of my Mac in any way?
3. What is the equivalent of securely wiping a SSD?

Thanks

This is an excellent brief guide to erasing drives:

How to Securely Erase a Mac’s SSD or Hard Drive - TidBITS

If you need to get rid of a Mac or external drive, how do you ensure that no one can access the data on it? Adam Engst runs through the various methods you can employ, one or more of which should address your situation.

tidbits.com

(TidBITS is a troubleshooting site that the founder of MacInTouch, another troubleshooting site that was well respected, recommended to users when he converted MacInTouch to a blog.)

Personally, what I would do depends on what a drive was used for and what kind of data is on it. If there is anything that is highly personal, sensitive, or confidential, I would destroy the drive, as described in the article. Why? Because even if current methods render the drive unreadable or unrecoverable, there is always the possibility a future tool, device, or method will be able to recover data. Plus smashing or drilling a drive doesn't take long at all and only requires a hammer or a drill. Easy, quick, effective!

 

[MallardDuck]

I have a bunch of old 3 and 4TB hard drives that I am going to get rid of, and I want to securely wipe them. I started securely wiping a 4TB drive late Thursday with the most secure settings and it is still going through the process as of right now on Monday morning.

1. Are the most secure wipe settings overkill for hard drives? What would it take for someone to recover my data using a lower secure wipe setting?
2. Is the process/speed of wiping the drive dependent on the speed of my Mac in any way?
3. What is the equivalent of securely wiping a SSD?

Thanks

Going forward, the best option is to always encrypt the drives, then when it comes time to dispose, you can just format them (destroying the boot sector info aka cryptoshredding) without wiping. Still recommend drilling them to be safe.

For unencrypted disks or SSD's, I format them then go to terminal, cd to /volumes/diskname and run dd if=/dev/zero of=./wipefile.txt bs=65536

That fills the entire disk with 0's. For 99% of the people, it's more than enough (unless you're a target of a nation state, multi-pass wiping is almost always overkill). Then I drill the disk and dispose.

If an unencrypted drive has actually failed, I open the drive itself up, extract the platters, drill them, and then bend with two pairs of pliers.

One note on SSD's - because of garbage collection, it's always good to encrypt them - that way if sectors are removed from access, there's no unencrypted data on them. That's one reason I drill each individual chip on SSD's when disposing.

And on encrypting - it's important to do before putting any data on it. Depending on how it's done, FileVault will not always encrypt unused space, so if you've deleted files or formatted the disk, you're likely to have leakage.

 

[Alpha Centauri]

If they were going into landfill I'd probably splatter them with a sledge hammer. Why? Because this truly would make the data unrecoverable whilst being a fun thing to do.

However, I've recently returned a 2TB SSD back to the retailer because of compatibility issues. The staff weren't 100% sure what will happen to the drive, some speculating it will be resold as an open box item. So there I was with collected photos, documents, etc from the last 50 yrs...personal stuff really.

I chose to 7-pass erase it. Why 7? It just made me "feel" better, safer. Had there been 9-pass, I would have done that instead. It wouldn't have made me feel an additional 2 x safer but it was the max available. Ahh..the human mind, wonderful. The only price I paid to "feel" better was it it took 5 days to complete. Couldn't use FW800 (patched OS) so USB2.0 it was.