Does copying on the fly really works in this case?

I just bought a NEC 2500A. My DVD-ROM is an ASUS E616P. When i copy on the fly a cd-rom with speed 24x, i notice that that the hard drive led remains on until the end of the recording process. The DVCD-ROM is working and the buffer is always at about 94%. I don’t understand why the HDD Led is always on sicne the recording speed isn’t that high and i select to copy on the fly. I have seen this in other PC’s also. My cpu is an Athlon 1ghz and motherboard asus a7v133-c

The LED is not just an HDD LED, it’s an IDE LED. It will light when ANY IDE device is in use, be that a CD-ROM, DVD-ROM, or anything on the IDE chain.

Then why it is not on when i access the cd-rom from windows explorer or any other application?

Good question! Perhaps as info is transferred it still has to be temporarily stored in HD ‘cache’ (once RAM runs out)? HD cache should be faster than CD drive speeds…