How Does a Copy Buffer Work?

I know this sounds like a very basic question and I guess it is for most of you. I don't know much about computers. My question is what does a copy buffer do within a computer? To help answer the question, let me explain that I'm trying to figure out how big I should make the copy buffer size in a program called FastCopy. I've been really trying but I don't understand people's explanation. It's too technical.

Let me start with my current understanding of how things work. (Don't worry if I get the small details wrong. Just let me know if the general idea is correct.) When you need to copy data from point A to point B, it's broken into data sizes called a buffer size. The CPU is given instructions to move the reading arm of the drive to the designated data area at point A. After it reads what the data says, the writing arm of the drive immediately writes the data inside the RAM. It keeps doing this until amount of data in the RAM is equal to the buffer size.

Then, at this point, I am guessing that the data is checked to see if there are any errors. If there is an error, the entire process starts again from the beginning of the buffer. On the other hand, if the data is correct, then the writing arm moves to point B and starts writing while the reading arm starts reading the data in the RAM. From my reading, it seems that errors happen infrequently these days. After the data is written at Point B, the process starts all over again.

If you have a small buffer size, there is a lot more movement of parts of the drive I guess which will increase the time significantly? The reading and writing mechanism of the drive has to be moving around a lot more. For example, with a small buffer size, data has to be verified bit by bit so the reading mechanism has to be moving from the RAM to the drive. Overall, a smaller buffer size makes copying take longer because the mechanism has to move around more. Is that right? On the other hand, if you create a buffer that is too large, and only one mistake is made, the copy process has to start all over again from the last buffer.

If this is all generally true, why don't people just create a large buffer size? It doesn't seem like many errors occur in reading and writing the data. Wouldn't increasing the copy buffer to something like 1 gig usually make everything much faster?

Its more complicated than that it only buffers if it cant be written and a lot depends on the buffer on the target ie hd add to that it may be blocked by AV scanning it as well. Increasing buffer can have no effect if the data cant be moved to the target

I can't answer but see posts #7, #10 and #15 here and maybe test?

All memory used when copying files from Truecrypt container - Windows 7 Help Forums