what is the bottleneck when copying file from CD?

Luis luis at anachreon.co.uk
Wed Jan 21 07:31:46 EST 2009


Hiya,

In the first instance, laptop hard disks are generally slower than  
desktop disks (7200rpm and laptops generally 5400rpm) although I  
can't see that this should cause such a large difference!

What filesystem are the DVDs formatted to?

Cheers,

Luis.



On 21 Jan 2009, at 12:04, Tiemo Hollmann TB wrote:

> 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
>
>
>
>
>
>
>
>
>
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