Re: [tlug] rsync vs dd [was Tlug Digest, Vol 14, Issue 23]

["Stephen J. Turnbull" <turnbull@??>]

Erin D. Hughes writes:
 > Tribble Phillip J SrA 374 LRS/LGRTT wrote:
 > > Good Morning,
 > >
 > > Does anyone know a good way to backup a hard drive? dd if=/dev/had
 > > of=/dev/hdc will make a image exactly the size of my hard drive. Is
 > > there a way to use DVD and make the image small?
 > >
 > >   
 > Philip,
 > 
 > I am not sure what you are trying to accomplish here.
 > Do you mean you want to compress the entire contents of the HD and then 
 > write it to a DVD?
 > 
 > dd will copy the hd from one location to another exactly as is same size.

However, I don't think this will work for CD or DVD; I doubt that dd
can do all the work the mkisofs and cdrecord do.

 > I would also suggest not copying the proc/ folder because of the fact 
 > that running process are there including your rsync process and it will 
 > just keep copying the instance of itself till it eats up all your disc 
 > space. So add  --exclude=/proc and you will be good.

I don't think that's true.  rsync makes a list of files that need
copying and copies each one, once.  Of course you don't want to copy
/proc, but more because the data is volatile and read-only, and big
(/proc/kcore, for example).  More important is that you don't want to
copy something like /dev/random or /dev/zero, which never return EOF.

I really think that rather than try to back up the whole hard drive in
one shot, you should back up /etc, /home, /var, and maybe /usr/local
and /boot.  /var should contain your pms state, so you don't really
need /usr, /bin, or /sbin.  /proc and /dev you shouldn't touch for the
reasons above.

If you really want to use dd, I would recommend partitioning the HDD
and using dd to write the partitions to files, which can be compressed
and burned to DVD.