If you are going to go to the trouble of smashing disk platters with a hammer, be sure to wear proper eye protection. A scratched cornea is no fun.
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Yes. And put it in a bag during the smashing, so you can capture all the shards.
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“palimpsest”
Yes. But…
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After you write zeros to a block, the data may remain for a while in flash cells marked as “garbage”, but that data is inaccessible via the normal SATA/NVMe interface.
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If you can remove the flash chips from the board and read them directly, you can probably see whatever garbage is left behind.
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I think it should be possible to install modified firmware into an SSD controller to allow access to garbage blocks.
I have not heard of anyone doing this, but I would be really surprised if such firmware doesn’t exist, either as manufacturer debugging tools or as forensic tools for law enforcement.
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The purpose of TRIM is to immediately mark blocks (possibly the entire device) as garbage. Effectively the same as writing zeros to everything, but much much faster and without creating excessive stress on the SSD.
When the actual garbage gets collected will still be an implementation detail
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There are actual “secure erase” commands in the ATA/SATA protocol and (if I remember correctly) the NVMe protocol, which, if implemented properly, should force immediate garbage collection.
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If you’re on a Linux system, there is the
blkdiscardcommand which can quickly TRIM-away devices or regions of devices. It has a “secure” option which will also purge garbage, if the target device supports the feature. -
But all of the above is moot if you use encryption. If you’ve encrypted the device, then all you need to do is discard/forget/lose the key and that’s that. The data will be unrecoverable.
Ever since the introduction of the T2 chip in Intel Macs, Apple has always encrypted the internal SSD. Wiping the device using Erase all content and settings, should do just that, quickly and easily destroying everything not pre-installed by Apple.
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Agreed, which is why it is annoying that since macOS 11 Big Sur, you can’t create a bootable clone by copying to an encrypted drive. You have to first clone to an unencrypted drive (using asr), then boot into it and turn on FileVault. So there’s a window where all your data is un-encrypted, and some of that data may be in pages moved to spare blocks.
A question: About 10 years ago, I took several old spinning disk hard drives (removed from their enclosures or PCs) into my local tech equipment recycling site for disposal.
They had a drill press there, and would drill a hole through the platters to securely destroy the data. The drive was never opened up – just drilled through the drive casing. (In fact, the process was “self-serve” – they let me drill it myself.)
Question: Is this a secure way to destroy an HD drive?
The drive will never work again, and any attempt to move those platters into a new enclosure will just result in destroying the new enclosure’s heads.
But that having been said, a determined forensic analyst could probably recover a lot of the data. Remove the platters, patch the holes with something leaving a smooth surface, and then transplant into a new enclosure. You’ll find a lot of bad blocks around where the holes are, but it may well be possible to read everything else.
But it’s unlikely anyone will do all that work unless they know in advance that there’s some really valuable data to recover.
So, I’d say it’s probably good enough for most people, but definitely not appropriate for highly sensitive data.
Unless, of course, the drive has glass platters (most 2.5" drives do), in which case, that drill will shatter them.
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“modern Macs use TB3”
I think you mean that Thunderbolt 3 and later use a different connector (USB-C) than earlier versions of Thunderbolt.
I’ve seensome vague summary reports about this.
I don’t have anything other than vague recollections that it kinda sorta worked but was really expensive. Certainly beyond the capabilities and budget of less than national status and certainly not worth worrying about for normal people. And even then it was really just segments so any sort of non textual info was probably not recoverable. This was something like going on 4 decades back so at this point IMO pulling the platters and beating them into bent up scrap is really more than sufficient I think. I realize that it might not be ecologically responsible…but the oceans are big and if one tossed a couple drive platters into salt water they’ll probably corrode pretty quickly. After all…probably most of a dozen nuclear powered submarines sank over the years and there has never been any reports of environmental impacts from those and a drive platters into salt is far smaller. At worst…put the bashed up platters into salt a box in the garage…few of us will ever have enough of them to fill more than a small Amazon shipping box anyway.
For most regular people this is mostly a non issue and even for those with client info smashing the platters and sticking them into the garage or hidden in the garbage collection is more than good enough IMo. Even if somebody for and sifficneniflattened the bent platters…disk layout and such is unknown…and unless one is a high value target the maybe might be juice isn’t worth the squeeze.
I think Erase Disk in the GUI only writes a new disk label and directory. The file data remains, the pointers to make easy use are gone. “Easy” being the keyword.
I’m old enough to get confused by all the versions of DiskUtil we’ve had. Once Upon A Time we had a means of testing media from the GUI. Thought it was still there as not too many years ago I abused a Seagate 8T drive for a week with it. Then decided the power supply for its former enclosure was the root of my problems. This drive has been serving well past year in a Ubiquiti NAS2.
As for finding faster interfaces to clear the old drive might I suggest the old interfaces were likely faster than the drives?
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I have repurposed two USB2 enclosures as local music libraries for Bluesound Node streamers. USB2 is the standard for audio file transmission. Without having done much testing, there seems to be no audible difference, in this use, between USB2 and USB3.
Yes. That’s the big difference between “erase” and “secure erase”.
If the volume was formatted HFS+, there are plenty of utilities that can “unformat” it, including Disk Warrior. This will scavenge the disk and re-create the directory structures from what it finds. It may not recover everything, but (depending on what was done with it after the erasure), it may be able to recover a lot.
If the volume was formatted AFPS, I don’t know of an unformat utility, but since software can still read all of the blocks, forensic analysis tools can see everything and recovery anything that’s not encrypted.
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I wouldn’t expect there to be a difference.
Uncompressed CD-quality stereo audio is 44.1 kHz with 32-bit samples (16 bits each for the left and right channels). That is about 1.3 Mbit/s. Well within the capacity of all but the slowest USB links:
- USB 1 “low speed” is 1.5 Mbit/s. Might work with CD quality audio, but probably not.
- USB 1 “full speed” is 12 Mbit/s
- USB 2 “high speed” is 480 Mbit/s
- USB 3 “super speed” is 5, 10 or 20 Gbit/s
Pro-audio encoding (typically up to 192 kHz and 48-bit samples (24-bit per channel)) might go as high as 9 Mbit/s . Still well within the capacity of USB 2, and might even work over USB 1 full-speed links.
Multi-track audio scenarios would push that even higher. 48 channels of pro-audio could get up to 211 Mbit/s.
In other words, there isn’t a need for more bandwidth than what USB 2 offers, so there’s little reason to pay for the expense (different chips and software) for USB 3 if all you’re doing is playing audio.
On Catalina, there are Secure Erase options one can choose from. I understand that those options were eliminated in subsequent versions of MacOS.
Yes. Apple removed these when SSDs became standard equipment.
Well, Apple claims it is still supported:
But I’ve never seen this option. I just went looking for it on two USB HDDs and on a thumb drive.
They never said why the option was removed, but the prevailing theory is that it is counterproductive on SSDs, and can lead to premature wear on the device.
Fortunately, the command-line tool did not remove these features, so third-party software isn’t necessary, although you might still find it useful.
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Just want to add that secure erase functions became less important when keeping disks encrypted all the time became easy and common.
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Thank you, David. Very useful indeed to have the number and exact parameters of both the transfer protocols and the audio files to be moved.
Am I reading your post correctly if I understand that USB3 “super speed” has a smaller bandwidth than USB2 “high speed” ?
No. Typo.
The Super Speed numbers should have been “Gbit/s”, not “Mbit/s”. I’ve corrected the post.
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Personally, I wouldn’t trust older drives, that have been sitting for a long time. There’s a high chance of failure. I would do the data scrubbing recommended by David Shamino and recycle them. I also agree with David that single pass erasure ( type 0 or type 1 ) is sufficient. I have been doing this with several drives recently, because I’m determined to get rid of the drives that I have which no longer have value (anything less than 1TB).
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