Like where does it go?
In: 3
I’ll throw my hat in.
Modern computing devices use addresses for the data. The operating system don’t know where the data is physically on the storage media, just the address so it can tell the storage media I want what’ at this address and the controller on the storage device knows where that is. For the sake of the explanation, we can make abstraction of this.
You can think of these addresses like street addresses. Basically, the operating system of the device “knows” where the data lives and that someone lives there, so it won’t have other data “move in” at that address.
When you delete data, it basically marks up the address as free and that new data can move in. It won’t necessarily get the old data to move out.
On a good old hard drive, that’s how it works. The old data is still living at that address and doesn’t move out until new data is told to move in. Now, if you want to make sure the data has moved out and is no longer there, you can write new data that doesn’t mean anything at that address. New data moves in, old data moves out. Now, that can leave some traces. Think of it as the old data moved out, but their furniture, belongings, etc. are still at that address, so it might be possible to figure out what the data was. That’s why to truly delete data on a hard drive, you write multiple passes of random data to make sure any traces of that data are no longer at that address. Of course, demolishing the drive would be like demolishing a house, it’s gone for good.
Solid state storage works a bit differently. SSDs have better performance if there is no need to overwrite data. That’s why something called garbage collection happens. Think of it as someone going through the neighborhood and making sure that addresses where data was told to move out are actually empty. It will make those addresses empty if it finds that it should be empty. There’s also something called a secure erase which makes the drive entirely empty.
Some other media like CDs can be write only and you can’t delete data from it. You can always physically destroy the CD to delete data.
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