[lug] Backup to 2nd HD with dd & rsync?

[D. Frye]

Thomas R. Detman wrote:
> I have two hard disks spinning in my workstation.
> I would like to use one as a backup for the other, 
> --> if it isn't too too complicated.
> One is a SCSI and the other is IDE.  (A result of history, not plan.)
> The SCSI is the one I use, it is 17 GB, ext3, with 4 partitions.
> The IDE could be wiped. It is 12 GB, ext2, with 2 partitions.
> Every thing stored on the SCSI only takes up only 10.5 GB.
> 
> Me thinks I'de start by using dd to copy the "stuff" on the SCSI 
> onto the IDE, wiping out previous IDE contents in the process. 
> (Doing such "stuff" is outside my envelope of knowledge and comfort.)
> 
> Next I'de set up a cron job to keep the IDE drive up to date as
> a "mirror" of the SCSI drive using rsync.  The rsync web page:
> http://rsync.samba.org/ seems to suggest this is just the kind of
> thing rsync was made for.
> 
> I think I might be able to muddle thru the rsync part, but even
> after reading the man and info pages on dd, it still seems like
> black magic to me.
> 
> Tom


I'm not sure if this will really work for you or not. I recently did a 
similar thing on a Solaris box to replace a disk, and in my research to 
verify the steps, I ran across a potential snag for you.

To paraphrase: if you use a bigger target disk than your source disk, it 
will make the larger disk appear smaller. This was a result of the 
Solaris disk label being copied over. If you wish to see the information 
in it's original form, I can send that to you, after I track it down 
again on Sunsolve. I don't know if you can use a bigger -> smaller disk 
combination.

Were it me, I would just run fdisk on the target, and then use rsync, 
and bypass the dd step, which will require the system to be booted off 
of alternate media for the initial copy of the disk anyway.

HTH,

David

-- 

D. Frye
dafr AT peakpeak.com
dafr AT freeshell.org
http://dafr.freeshell.org/