Re: Improved cloop driver

On Thu, Jul 01, 2004 at 03:54:27PM +0200, Tim Botzelmann wrote:
> Hi Michael,
> 
> Michael Cohen sagte:
> > Also you will
> > need to know in advance how big the uncompressed image is so you can make
> > a
> > large enough empty index at the start - this may not be easy to know if
> > you
> > just do a mkisofs for example,  and pipe the result to the compressor.
> 
> mkisofs does tell the size of the image if started with the option
> "-print-size" added, so the time penalty wouldn't be that big if this was
> needed (just going through all the files and counting the blocks needed
> for the image).


This doesn't help if you want to compress an entire harddisk partition
regardless of the file system type. You would have to tell
create_compressed_fs the total number of blocks to reserve for the index
(which is possible for harddisks). However (adressing Michael), I still
see no reason for a change in the cloop format, since this change can be
done in create_compressed_fs, and the extra 1-3MB of index/overhead ARE
a problem for the CD edition of Knoppix, where I have to spend hours in
searching for a few extra bytes to delete in order to still fit into a
700MB space. Plus, scanning the header of a file is much quicker than
seeking to the end or computing the size of each compressed block.

Regards
-Klaus Knopper