QUOTE(llsTixll @ Nov 26 2008, 12:08 AM)
Can someone please help me understand this statement:
"So then the real question is why is copying from HDD to HDD slower than copying from DVD to HDD? In the first case, you are reading from one I/O device (HDD) and writing to the same I/O device (HDD). In the second case, you are reading from one I/O device (DVD) and writing to a different I/O device (HDD). In the first case, because we are reading and writing to the same device, the total copy time is the amount of time it takes to read the map plus the time it takes to write the map. Ultimately this is because for the HDD, you read and write through the same mechanism, i.e., the hard drive read/write head, and those reads and writes cannot occur simultaneously through a single mechanism."
As a test on my PC, I copied some data from my optical drive to the hard drive and it took 4 mins. Copying the exact same data to another location on my hard drive took 45 seconds.
How can they say copying from DVD to HDD is slower than copying HDD to HDD?
This is a good question but a completely different circumstance.
On a PC, the computer knows its copying from itself to itself so instead of copying the data, it just modifies the file system to tell the Hard drive the data is located at this new location.
No ones and zeroes of the actual data are moved, just file system tags are changed. This is also the reason Fragmentation happens.
On the xbox, Halo 3 takes the actual map data and loads it to a special section on the hard drive set aside for JUST game data, nothing else. Halo 3 doesn't know its loading off of the hard drive, and just checks to see if the game data is in this special hard drive area. If its not there it copys it over, even though its already on the hard drive.
Since a Hard drive cant read and write at the same time (And for that matter, a DVD burner couldnt either), it takes longer then reading from one device and transfering to another.