what is the bottleneck when copying file from CD?

[Tiemo Hollmann TB]

Hello,

I have to copy about 7 GB in 6 zip files from DVD-ROM to HD.

I do it by a repeat loop with read - write - see below.

 

Because I experienced very big performance differences on different
machines, I made extensive tests on different machines and different read
chunk sizes in the repeat loop.

First I experienced that the chunk size for reading has almost no influence
on the total time. Tested with a chunkSize of 100K, 1MB, 10MB, 100MB.

But I experienced very big differences on different machines. Total copying
time for 6,7 GB varies between 27min on a PC Desktop (Core 2, 2,66Ghz, 2GB),
49 min On a Vista Notebook (Core 2 Duo, 1,86 Ghz, 2GB) and 93min on a
MacBook (Core 2 Duo, 2,2 Ghz, 2GB), what meant a put through of 4,1 MB/s on
the PC and 1,2 MB/s on the Mac.

 

I am not the hardware or system guy, so can anybody shed some light on these
differences. What is the bottleneck and is there anything I can do in my
script, or do I have to tell my customers "Installation time can vary
between half an hour and two hours :-( ." and it is just like it is?

 

Thanks for any hint or experiences

Tiemo

 

 

The code snipped is:

    open file tQuellFile for binary read

    open file tZielFile for binary write

    repeat until it is empty

        read from file tQuellFile for gChunkSize #a global for testing

        if it is not empty then

            write it to file tZielFile

        end if

        add gChunkAdd to tMB

        set the thumbpos of sb "Progress" to tMB

        put tMB && "MB von gesamt ca." && gGesamtSize && "MB kopiert..."
into fld "fldMB" # progress in MB

        if the uCancel of this stack is true then

            close file tQuellFile

            close file tZielFile

            answer "Abbruch"

            exit to top

        end if

        wait 1 millisecs with messages # wait 0 didn't worked, no click on a
button was accepted

    end repeat