AW: what is the bottleneck when copying file from CD?

[Tiemo Hollmann TB]

Hi Florian,
good advice to look for the block/sector size. Didn't knew, that they are
still this small :) I'll give it a try with smaller chunk sizes.

Would be interesting how big the sector size on a Mac HFS+ is. If it differs
to Win, I could work with two different chunk sizes, depending on the
system.
Perhaps anybody knows?
Thank you
Tiemo


> -----Ursprüngliche Nachricht-----
> Von: use-revolution-bounces at lists.runrev.com [mailto:use-revolution-
> bounces at lists.runrev.com] Im Auftrag von Florian von Walter
> Gesendet: Mittwoch, 21. Januar 2009 13:52
> An: How to use Revolution
> Betreff: Re: what is the bottleneck when copying file from CD?
> 
> Tiemo,
> 
> first your chunk sizes are too big. The copying speed is largely
> dependent from the sector size of the media you are copying from and to.
> The standard DVD sector size is 512 bytes iirc. The sector size on the
> disk of the computer you are copying to is dependent from the file
> system being used and how it was initially set up. The standard sector
> size for NTFS under Windows nowadays is 4096 bytes (4k) but it can vary
> from 512 bytes to 16k. For FAT I don't know the sector sizes. For HFS(+)
> under MacOS I also don't know it.
> Second the copy speed for DVDs depends heavily on the DVD drive itself
> (i.e. the firmware) and how the OS driver is implemented.
> Third OS caching also comes into the picture.
> 
> I would recommend to try to use a chunk size of 4k maximum (also try
> 0.5k to see if this is faster).
> Bigger chunk sizes don't make sense because they probably just replicate
> data what is in the OS file system cache anyway (and therefore increase
> the memory footprint of your application).
> Everything else imo depends on factors you cannot influence.
> 
> Regards, Florian
>