(Question asked by reader Tevin Gotti*.)
No, it’s not true. Lots of data gets permanently deleted all the time.
Data that’s been fully and completely overwritten is beyond recovery.
But it takes extra steps to “fully and completely” overwrite data. When that’s not done, all bets are off: It might be possible to recover old data.
Just deleting a file leaves virtually all of its data intact. Likewise, a standard drive reformat may erase the information the OS uses to find the files, but may leave the actual file contents intact, or nearly so.
Deleted/reformatted data mostly remains untouched until and unless it’s overwritten by new data, such as when the operating system re-uses the same space on the HDD or the same cells in the SSD to store a different file.
When overwritten even once, most data is beyond recovery by standard, off-the-shelf file-recovery, “undelete” and “unformat” tools.
After several overwrites, the data is beyond recovery by all but the most exotic, sophisticated, and expensive means — think research labs and very-high-end forensic labs.
After many overwrites with random data (e.g. by high-quality “drive wipe” software, running for a long, long time), the data is effectively unrecoverable by any normal means.
There used to be concerns about world-class, national-government level forensics being able to recover very faint data traces left in the space on the disk surface between the actual data-tracks; but that was when hard drives were much less capacious than today. Now, tracks are so tightly packed that the odds of this kind of successful data recovery are vanishingly small, especially if the drive has experienced multiple overwrites with random data.
And even if there are exotic, top-secret, advanced, Hollywood-fantasy-level recovery methods that can extract data from a thoroughly-overwritten drive, is that really a concern for you? Are you a target of spare-no-expense governmental-level hacking?
If so, then you need to shred your drive into tiny pieces, or melt it into slag. That’s the ony way to be 100% certain that no old data can be recovered.
But why worry about hypothetical types of attack that you are extremely unlikely to ever experience?
For normal people in normal circumstances, reformatting a drive, and then wiping it with at least one pass of random data, is perfectly sufficient to ensure that the drive’s previous contents will not be recovered.
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