Re: [Qemu-devel] Os ZOO: images will be available. Questions...

[Herbert Poetzl]

On Thu, Apr 29, 2004 at 07:30:29AM -0700, Kyle Hayes wrote:
> On Thursday 29 April 2004 05:05, Stefano Marinelli wrote:
> > Hi there. So I asked and all the image (free oses, of course) will
> > be available for download. They will be put on ftp on the
> > department's machines. Windows will be restricted to local users
> > but the several BSDs and Linux will be available for anybody. The
> > matter now is...I will create images for local users, so something
> > like 1GB images. But it could be difficult to download 1GB images
> > from another place (non-local). How could I solve? growing file
> > systems?
> 
> bzip2?  It will compress things very well.  Even a relatively large 
> image will compress by a large factor.  Most of each image will be 
> either empty disk space (huge compression factor), or things like 
> binaries (about a 2x compresion factor).

it's a good idea to install whatever OS on a
zeroed out disk image, and if possible cleanup
the unused space by either writing a large file
of zeroes or erasing unused space ...

> Use the "best" compression method (-9) to get the largest compression 
> factor.

JFYI: from the bzip2 manpage:

       -1 (or --fast) to -9 (or --best)
              Set the block size to 100 k, 200 k ..  900  k  when
              compressing.   Has  no  effect  when decompressing.
              See MEMORY MANAGEMENT below.  The --fast and --best
              aliases  are  primarily for GNU gzip compatibility.
              In particular, --fast doesn't make things  signifi­
              cantly  faster.   And  --best  merely  selects  the
              default behaviour.

       bzip2 compresses large files in blocks.   The  block  size
       affects  both  the  compression  ratio  achieved,  and the
       amount of memory needed for compression and decompression.
       The  flags  -1  through  -9  specify  the block size to be
       100,000 bytes through 900,000 bytes (the default)  respec­
       tively. 

best,
Herbert

> Best,
> Kyle
> 
> 
> 
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