AW: what is the bottleneck when copying file from CD?
Florian von Walter
fvwalter at web.de
Wed Jan 21 08:35:30 CST 2009
HFS+ sector size seems to be 512 bytes according to
CD-ROM sector size is 2352 bytes gross and 2048 bytes net according to
DVD-ROM sector size is 2418 bytes gross and 2048 bytes net according to
http://en.wikipedia.org/wiki/DVD-ROM (so I was wrong with my 512 bytes).
Tiemo Hollmann TB wrote:
> 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
> Perhaps anybody knows?
> Thank you
>> -----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?
>> 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
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