On Fri, Oct 24, 2003 at 08:55:16AM -0700, Dege, Robert C. wrote:
> 
> Thanks for the info Paul (and Jay).
> 
> 
> Paul, a few additional questions directed towards your response.
> 
> > In my experience the compress best uses 4 times as much CPU for only
> > 5% better compression, so it's not worth it, unless you have spare CPU
> > cycles to burn.  Maybe it's better to increase the dumpcycle (maybe
> 
> Is this 5% difference you're referring to between compress-fast vs.
> compress-best?

I've done similar measurements to Paul's and while I found a bigger difference
between --fast and --best (aka -1 and -9 with 7 more gradations between) it was
not huge.  And yes, we are refering to compression of say 45% reduction with
--fast vs say 55% with --best.  But as Paul indicates with a 4x (I saw 5x)
increase in cpu usage.  What I also found was the writers of gzip picked a
default of -6 which in my tests gives the bulk of the increased compression
for only about 1.8x cpu usage compared to -1.  The improvements in compression
at levels -7, -8, and -9 were tiny for the increased cpu usage.

> > Right.  If you think a litter more about this, the amanda server does
> > not need to be the computer that runs smbclient.  My amandaserver has
> > already his cpu fully loaded, and two other machines do the smbclient
> > backups for my window machines, and they do the compression too.
> 
> 
> How could I offload the smbclient connections through another machine?  Are
> you implying an smbmount on the client, or is there some trick with
> smbclient that I'm not thinking of right now?

If hostA is the amanda tape server (also its own client possibly) you probably
have disklist entries like "hostA //pchost/xyz".  But if you have other unix
systems that can do samba too (say hostB), just change the quoted string to
use hostB instead of hostA.  If hostB does client-side compression then the
compression burden is offloaded from hostA to hostB.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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