Subject: Re: Tape access over net
To: None <wojtek@wojtek.from.pl>
From: Jukka Marin <jmarin@pyy.jmp.fi>
List: netbsd-users
Date: 04/01/2001 13:36:22
On Sun, Apr 01, 2001 at 12:11:10PM +0200, wojtek@wojtek.from.pl wrote:
> > I'm trying to write to a DAT drive over 100 Mbps Ethernet using ssh..
> > something like this:
> > 
> > tar -c -v -f - -T /var/run/tapefilelist |
> >   ssh -c blowfish sysfoo buffer -m 4m -p 25 -B -o /dev/rst1 -t
> > 
> > This works, but is very slow and I can only fit about 3.2 GB on a 4 GB tape.
> > CPU load on both machines is less than 5% and net usage is about 500 K/s.
> 
> ssh uses lots of cpu for scrambling

Yes, but if CPU load is under 5% (95% idle), it doesn't explain the slow
speed.  I guess the DAT drive writes some data, then stops, rewinds the
tape, writes some more data etc.  But why?  I have a 4 MB buffer which should
be enough to keep the tape streaming, IMHO..

  -jm