fastest raw device copy?

[Jerry McAllister]

On Fri, Oct 31, 2008 at 09:48:16AM +0100, Christoph Kukulies wrote:

> Hi list,
> 
> I'm considering using a bootable USB stick with FreeBSD to perform a 
> backup of my notebooks'
> 500 GB hard disk to a physically identical (same make, same type, same 
> size) hard disk attached to  USB.
> 
> What would be the fastest way to do that sector by sector copy? I'm 
> using dd right now,
> 
> dd if=/dev/ad0 of=/dev/da0 bs=10000000
> 
> but maybe there is a utility which does this faster or a larger buffer 
> size? Probably the limit will be
> the USB 2.0 bus speed anyway?

Are you sure you want to do a sector-by-sector copy?
That won't get you much that is useful in terms of a backup.

Can't you use dump/restore instead?

Dump each file system on /dev/ad0 to a file on /dev/da0.

Create a file system on /dev/da0 using newfs first.   You may or
may not want to create a FreeBSD slice and partition there before
doing the newfs.  
Make a mount point and mount it.

mkdir /bkmnt
mount /dev/da0 /bkmnt    Or if you created slice and partition in /dev/da0
                         mount /dev/da0s1a /bkmnt

Then do the dumps

  dump 0af /bkmnt/rootbackup /
  dump 0af /bkmnt/usrbackup /usr
  dump 0af /bkmnt/homehackup /home

etc for whatever file systems you want to back up.

You will be much better off than with a sector by sector copy.

////jerry
 
> 
> --
> Christoph
> 
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