Basically, when a file is written to a hard drive, it is written to free space sequentially from start to finish. But what happens when there is not enough continuous free space to fit the entire file?
The file gets fragmented, meaning that one part is written to one strip of free space, second part into another and so on, until the entire file is written.
This means that when later accessing the file, the hard drive reads the first part and then has to jump to the next part, that may physically be stored in a completely different place on the drive. This jump takes considerable amout of time, leading to worse performance.
Defragmenting rearranges the files such that each file is continuous in one place, reducing the number of jumps, improving read performance.
Now that every computer has an SSD in it which does not move physical heads, these jumps do not take virtually any time and, therefore, defragmenting is no longer necessary.
Basically, when a file is written to a hard drive, it is written to free space sequentially from start to finish. But what happens when there is not enough continuous free space to fit the entire file?
The file gets fragmented, meaning that one part is written to one strip of free space, second part into another and so on, until the entire file is written.
This means that when later accessing the file, the hard drive reads the first part and then has to jump to the next part, that may physically be stored in a completely different place on the drive. This jump takes considerable amout of time, leading to worse performance.
Defragmenting rearranges the files such that each file is continuous in one place, reducing the number of jumps, improving read performance.
Now that every computer has an SSD in it which does not move physical heads, these jumps do not take virtually any time and, therefore, defragmenting is no longer necessary.