I've installed Ubuntu 12.04 using the normal installer. Things having been working fine, but a few minutes ago I copied a 14Gb file and it said it had copied the file very quickly--so quickly I don't believe it. I was hoping that someone could give me some insight into what Ubuntu is doing here. Is it just making some sort of link to the file or perhaps continuing to copy the file in the background and not telling me? Thankyou :)
Generally you will see a progress bar if you use Nautilus to do the copy, however a key part of how Linux gets great disk performance is through disk buffering. At any time a large proportion of the available free RAM can be given over to disk buffering.
You can get some idea how this is working if you type
in a terminal window. Under the Column 'free' you will see three figures. The first is the actual free memory, while the second is the free memory less disk buffering. The third figure is of course free swap memory, which we are not really concerned with here.
If you are copying a file from one partition to another you should indeed see a progress bar and it should take an appreciable amount of time. An icon for it will appear immediately in the target folder (in Nautilus) however.
Another key point is that if you are actually moving a large file on the same partition then it really takes no time at all since only the logical pointers to the data need to be changed.