How HDDs recovered?

[hack3rcon]

Hello all.
When, I remove a file from HDD and write other file, How Recovery program recover it? My previous data is removed and if it is not how new data written?

Thanks.

[hack3rcon]

If a sector written by other files, Recover the previous files are impossible? Even by NSA and FBI ?

[hack3rcon]

Modern Hard Drive?
How about SAS? I guess they are recoverable.

[digitalferret]

Hi hack3rcon

When you "remove" (delete) a file, the computer marks the space it occupied as available to be written to again.
It does not wipe the space clean unless instructed to do so directly with an erase program or command.

When you write a file back to the computer, it chooses where to write to disk and this may not be over the space previously occupied by the file you just deleted.

The file may even be larger than the spaces that are free so the new file is split into many parts and written across multiple locations across the disk.

Successful recovery depends upon many factors.
What you want recovering, how and where the required data was stored, how files were deleted / wiped, what size the files are, how much free space is on the disk, how badly the disk is fragmented, temporary file storage, pagefile ...
The list goes on.