[Techtalk] dump and compression

[James]

On Mon, 15 Jul 2002, Conor Daly wrote:

> Puzzled here...
> 
> I'm using dump to backup to CDRW.  If I do
> 
> dump -0 -B 665600 -f dump.dat /
> 
> I get a file dump.dat 650Mb in size.  That gets burned to CDRW before dump
> continues and uses the same file for the next bit.  I can backup a 2Gb
> partition in about 4 CDRWs.  If I use dumps compression option thus:
> 
> dump -0 -B 665600 -f dump.dat -z9 /
> 
> I get a file dump.dat about 215Mb in size and dump happily announces that
> it hasachieved 3:1 compression.  But, I wanted dump to stuff as much
> compressed data as possible into a _650Mb_ file!  Id there something I'm
> missing?  I suppose I could use the tape length options to specify the
> media size instead but it just don't feel right.

This is fixed in dump v 0.4b23 (released July 20, 2001). Check dump.sf.net 
for the latest version. (Another compression related option added was the 
"-j" switch, to use bzip2 rather than gzip compression - the added 
compression may be useful to you?)


James.