[luau] use dd for disk clone?

[burnst001 at hawaii.rr.com]

I am looking for a way to make a disk image or disk clone,  
found the following in a linux list archive.   
   
<quote>   
   
Subject:      Re: Linux disk cloning tool ?   
   
Yes--look at the man page for the dd command.  It copies raw   
disk images and   
why not use it for ghosting?  It's a simple, one-line command   
entry.   
   
<end quote>   
   
Being a newbie, I looked at the man page but was not   
enlightened.    
  
dd seems to be file oriented, but I guess you   
can just treat two mounted disks as files? What would that  
look like, use /dev/hda and /dev/hdb as stdin and stdout,  
something like that? If you use / it would cause a problem 
because you'd be including your destination in your source, 
right? 
  
Isn't there also an issue regarding open files, etc.? When I  
clone a disk in irix, the manual says to do it in single user 
mode, I presume because you want all the files in a consistent 
state.  
  
Anyone see a way of using dd to make a disk image file instead  
of cloning a disk?  
 
I found some other software at  
<http://systemimager.org/download/> that sounds like it would  
do the job, but I hate to clutter up my system if it is  
redundant.  
 
Would tar do? Tarball too big? Would tar be able to make an 
exact copy? Would it leave out .files? 
 
Delirious Dave