Maurizio Caloro writes:

>please let me know with what you are save the hole 
>netbsd on your machine .....

I you want to backup whole filesystems (full or incrementally),
dump(8) is the way to go.
Unlike all other programs, dump reads directly from the disk device,
and doesn't go through the filesystem interface, and tries to stay
as consistent as possible with live filesystems.

>i have proved with Tar direct to my dat tape but its realy
>hard to do, have you any better way to do this job,

Well, DAT is a write-only medium, like /dev/null.  You shouldn't
rely on getting your data back in any emergency case.  (I'm also
using DAT at home every now and then, I know what I'm talking about.)
Dump of course works with DAT.  But again, you shouldn't put any
trust in Digital _Audio_ Tape.

-- 
Matthias Buelow;  mkb@{mukappabeta.de,informatik.uni-wuerzburg.de}

    ``Entia non sunt multiplicanda praeter necessitatem.''
        -- William of Ockham (~1285-1349, "Occam's Razor")