Isn't that the same thing as over writing with the same file name?

This answer is not correct. The post describes a file allocation table as if it were in the beginning of memory. In the simplest designs, the file allocation table is at the beginning of the storage volume, not in memory. In more complex systems, such as distributed file systems, the file allocation table can be stored completely separate for the data storage systems.

There are two things these sites do: DNA sequencing and genealogy.

Genealogy is a big field. Lots of people, both professional and hobbyist, spend hours combing over public records or walking through graveyards, taking careful notes. They build very detailed records of who is related to who based on these records.

But those records are often incomplete. Sometimes the father isn't reported at birth. Some children are born in secret and not recorded. Sometimes birth records are falsified. Genealogists ALSO try to figure that stuff out. Sometimes people who find out their parents weren't biological hire detectives to try and put together where they came from. If that gets back to a genealogist that can help them piece together more accurate records. (I had this happen, I found out when I was around 19 that certain aspects of my family tree were lies to cover up some things a different family member was too embarrassed to admit.)

The most extreme cases are things like the fertility doctor who was using his own sperm on patients instead of the donors they had selected. There are dozens of people we know have incorrect biological lineage because of him, and we're not 100% sure how many more there might be because he wasn't consistent and even he can't remember every time he did it.

DNA sequencing helps do that. If it finds a close match, some detective work might reveal there was a birth that wasn't reported properly. Sometimes it's just coincidence. Sometimes the people who know the truth all dead. But generally if people match enough and have parents who were geographically near each other roughly 9 months before their birthday it's not a stretch to assume there might've been a misreported birth.

But if you can do the hammer delete then it's way better, since someone might be able to recover your stuff if not sufficiently deleted

But pray, tell, what button do I press to make my machine go? Red, or green?

There isn't really (official) publicly available software to do this, but depending on the storage technology you can often tell not only the current binary state of a memory bit but also the previous one.

As an example, we might say a bit is on if it is at 5V and off at 0V. However, real bits have voltages that vary quite a bit and we just threshold at (say) 2.5V. The actual voltages depend on (among other things) the previous state of the bit. If AB denotes a previous state A and a current state B, you might have something like:

00 -> 0.5V 10 -> 0.9V 01 -> 4.1V 11 -> 4.5V

Note that is doesn't quite work like this. The main point is that with dedicated hardware you can try to read data that has been lightly overwritten. This is why tools intended to purge data will overwrite many times with random bit sequences to minimize the chance of data recovery.

That correlates to stoplights, since green means it's SAFE to go and read means STOP, due to DANGER of an accident.

Imagine a binder with a table of contents, inside the binder there are pages, when deleting a file you just erase the page number, the page is still in the binder but you no longer know where to look. (If you want to find the pages again, there is special software, akin to looking through the binder page by page)

Some documents are several pages long, so when you later write something to the binder and replaces the pages, you might have page 4,7,9 of your document left, thats when it cannot be recovered anymore.

One of the things that determines whether a drug is available over the counter versus behind the counter or by prescription isn't just the potential for harm in case of overdose, but the potential for abuse and the potential for affecting public health. For example, if everyone could just grab amoxicillin whenever they want, we'd probably end up with a bunch of strains of medication resistant bacteria because a lot of people would take it every time they got symptoms that felt like being sick and wouldn't take enough for a long enough time to kill off all the bacteria exposed to the drug. Epinephrine has potential to be abused as a stimulant.

It's worth noting that if you're not on a windows machine or a OS X machine you may need to manually configure TRIM, as many *nix distributions do not have it enabled by default

This is a really cool analogy, props

My favorite anecdote is the story of Joseph James DeAngelo.

So generally speaking, if you're a normal consumer user of tech, deleting a file just deletes a record on your hard drive that points to where the memory address that locates your data is. The data itself isn't actually deleted unless you do a memory wipe. It will eventually be overwritten, because any memory that isn't reserved by a set of records is considered "free" to the OS to overwrite, even if there was previous data there, but until that point that data still exists there.

You can truly delete a file by wiping the memory (usually done by taking the set of memory for the file and overwriting everything to some empty state). But the default that happens when you delete a file doesn't do this because it's computationally expensive to do this when there's no real reason to.

As a security tip, if you're ever trying to actually delete data from a computer in a way that ensures it's not accessible, you want to do a memory wipe and overwrite the entire drive to an empty state. Just "deleting" the files will actually leave all the data there and just delete the records that say where the data is. Anyone good with computers can recover all of that unwiped data despite there not being a stored record for it because the data is never overwritten. Always fully wipe your drives before transferring ownership of computers with sensitive info.

Programs like Recuva do it for you. In the basic mode it is just reading all the entries that are marked as deleted.

The question title does not match the question body. Memory and storage are distinct components in many systems.

Most memory systems require an active power source to maintain the values stored in it. As soon as power is lost the energy in the memory begins to shrink and what was in the memory is lost

Storage keeps data even when the power is off. Early types of storage were much slower than memory. Deleting a file is done by changing the values stored. How the file is deleted is determined by a combination of the program deleting it, the operating system being used, the storage format, and the specific storage hardware.

The Guardian article has more information: "Sharon Highsmith said her family connected with a clinical laboratory scientist and amateur genealogist named Lisa Jo Schiele to help them with interpreting the key DNA results and mining publicly available records to locate Melissa."

FWIW, local TV news web articles are a terrible source. If you have any interest at all in the thing being covered, Google a few keywords and find a better article.

Thanks! And yeah, please do share it around! I've seen so many students office workers whose gait have been affected by heavy schoolbags (also because single strap looks cool).

The article is confusingly written so it's hard to figure out entirely, but obviously her records, or someone already linked to her were in the database.

DNA analysis and the databases are so well populated at this point that they can often "find" missing people via gaps.

Here's an anecdote - In my family an unknown person did a test which connected her to my family, people who already took the test. The system said you must be related to these people. Now my father also took a test but didn't give his personal information, so the system knew both my extended family AND that this person was downstream of my Father specifically but didn't know who he was or how to reach him. She was able to contact other extended family who said my father had the following children, one of them must be your biological parent. The woman was able to easily look at ages and genders at this point and identify her missing biological parent who wasn't in the system at all. Low and behold through the miracle of Social Media, this person got that "Hi, I'm your adult child" phone call.

You can still recover data post delete and TRIM on modern SSDs. The methods available for modern SSDs are certainly less reliable and consistent then in the past but certainly not impossible.

I read an anecdote about a programmer that wrote some sort of script that worked too fast and didn't look like it actually did anything. He added sleep counters and a progress bar to make it seem like it was doing something. A year later he "optimized" the program by cutting the sleep timers in half.

Until you crash shortly after saving and the file shows it's corrupted.

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Unfortunately the story doesn’t go into detail on who the “two boys and a girl” are, so I can only assume that they are Melissa/Melanie’s children. If one of them took a DNA test, it would show DNA matches. The story just doesn’t say where that information came from.

Without testing, you would have no idea. So there must have been someone down that family line that was tested.

Edit: you could always hop over to Twitter and ask the reporter for clarification

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