Read and write speeds, why the difference?

[Steinway]

So while I was looking for a laptop replacement, the question came to mind about "why is it that for storage solutions in general, why is it that read speeds are faster than write speeds?"

 

From all the articles and forum posts I've found, none of them really provide an answer to my question.

My first though was that it would be a controller or storage medium related aspect, but I know I could easily wrong, so I came here hoping someone could shed some light on this for me.

 

Cheers!

[NohbdyKnows]

ask yourself......is it faster to read an essay or write one?

[Sarcasm]

Well is it easier to read a paragraph or write it out? Same idea.

[technovore]

If I think about it on a hardware level, I'd say you read data faster then you write it because if you read you just have to perieve the current state of the data, but when you write something you have to physically change the state of the data, which takes time.

But that's just my hypothesis, I could be miles off.

[Steinway]

ask yourself......is it faster to read an essay or write one?

 

Well is it easier to read a paragraph or write it out? Same idea.

 

Neither of these answers actually help, I was looking for a technically sound answer, not an analogy.

[Flojer0]

If I think about it on a hardware level, I'd say you read data faster then you write it because if you read you just have to perieve the current state of the data, but when you write something you have to physically change the state of the data, which takes time.

But that's just my hypothesis, I could be miles off.

You're hitting the nail pretty closely.

 

With hard drives read and write speeds are practically identical last I heard. But with flash memory there is a time period necessary to program a memory cell. I can see if I can find a good article on it but essentially to read you put some voltage into some pins and get a value out of some different pins. To write you have to erase what is in the memory cell and then put a certain voltage on for a certain amount of time depending on the value you wish to program in.

 

As an example this also explains why trim is important. If you have pre-erased blocks (made up of cells, storage drives deal with data at the block level) available your SSD can use those and just remove the old blocks from the table telling it where everything is. When you erase data it doesn't get physically erased immediately and over time you will run out of empty blocks and the SSD will have to go through the erase/program cycle every time you write new data to disk.

[sperkowsky]

its easier to read a book then to write a book isnt it?

[technovore]

You're hitting the nail pretty closely.

 

With hard drives read and write speeds are practically identical last I heard. But with flash memory there is a time period necessary to program a memory cell. I can see if I can find a good article on it but essentially to read you put some voltage into some pins and get a value out of some different pins. To write you have to erase what is in the memory cell and then put a certain voltage on for a certain amount of time depending on the value you wish to program in.

 

As an example this also explains why trim is important. If you have pre-erased blocks (made up of cells, storage drives deal with data at the block level) available your SSD can use those and just remove the old blocks from the table telling it where everything is. When you erase data it doesn't get physically erased immediately and over time you will run out of empty blocks and the SSD will have to go through the erase/program cycle every time you write new data to disk.

Interesting, but I'm just happy my speculation was close! *happy face*