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I use a shared MacBook Pro with Catalina; I've done some basic research into deleting files but worry deleting too often will shorten the life of the drive (this is for a machine bought in April 2020).

In general, how easy is it to recover a file from an SSD as compared to a HDD, especially if you want to ensure something is permanently deleted with little chance of recovery (more sensitive files like medical etc. that you've copied elsewhere).

I've only ever used Mac minis as Mac computers before now so aren't quite familiar with this.

I did try Edenwaith's Permanent Eraser but is this overkill?

If anyone can guide me on this I'd appreciate it.

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You don't need to worry about either the security of the deleted file(s) nor the life of the SSD.

In general, how easy is it to recover a file from an SSD as compared to a HDD,

It's virtually impossible.

When you "delete" a file on an SSD, it tags the blocks as unused and depending on the scheme that it uses (DRAT or RZAT) when the block is subsequently read, it will either return zeros or it will return random data (garbage). Tagging it as "unused" means the drive will recycle it for the next set of writes rather than writing over it to erase and then writing again with actual data.

In the second linked post, it talks about how the command srm (secure delete) is no longer available in macOS. It's because it's no longer necessary. It's virtually impossible to retrieve data once it's deleted from an SSD and if you enable encryption (File Vault), it's gone forever.

Unlike a traditional HDD, when you delete a file, it doesn't overwrite the file either. Instead, it deletes the pointer to the file. Since the data wasn't overwritten, it was easy to recover.

You will outlive your SSD

The short answer here is that you simply cannot write enough data in your lifetime to worry about wearing out an SSD. You are more likely to outstrip it's capacity or for it to fail due to a component failure before it wears out.

Limited Read and Writes on MacBook Air SSD

Using Intel's SSD life span calculator as a basis for the calculation, you'd have to take and save 24,0000 digital images per day for the rest of your life to wear out an SSD.

TL;DR

  • You don't overwrite data when you delete on an SSD so wear isn't a concern.
  • Retrieving the data from a deleted block on an SSD is next to impossible because of the way data is retrieved
  • You can't write enough data to your SSD that wear would become an actual issue to deal with.
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  • thanks! I have a question. apple.stackexchange.com/questions/269863/… in here you answerd "(that's a whole different issue), you should replace the drive." Does this mean that automatic deletion of trim in ssd does not prevent forensics? In terms of probability, what percentage you guess? – roun paleum Mar 30 at 12:04
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Deleting will add extra writes to a SSD. However, unless you plan on doing many GB per day the overall impact should not be noticeable.

Recovery is harder than a classic hard drive. A SSD has hidden storage that it uses for wear levelling and covering any worn out parts of the visible SSD storage. A SSD internally is jumbled up as it tries to prevent any constantly overwriting file from burning a hole in the drive by spreading writes around. It only pretends to look organized. You can try to erase but you cannot easily guarantee a full overwrite. Perhaps there are SSD specific erasing apps.

Since the extra storage cannot be easily accessed (and a SSD will reshuffle the drive to evenly spread out the wear and tear) you should consider full drive encryption. This makes all the storage always scrambled if you are not logged in.

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  • Thank you! I'm only really planning on deleting 7GB of files as a one-off, with 4GB being sensitive stuff. I don't want to get them recovered but if I did sell off the Macbook pro in the future, ensuring that it'ss afe enough. Full drive encryption I don't know about since it's a shared computer. – avenas8808 Oct 27 '20 at 9:51
  • Deleting does not add extra writes to an SSD. Recovery is virtually impossible; when you encrypt the data, it's then completely impossible. – Allan Oct 27 '20 at 17:34

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