How to mirror a harddisk for backup purpose

alvin at alvin at
Fri Jun 22 03:20:34 PDT 2001

hi kwan

i would use tar to copy disks onto antoher disk...

# copy hda  onto hdb...
dd if=/dev/hda  of=/dev/hdb bs=1024

BUT..BUT...dd is bad ...
	- it copies bad block info fron disk-a onto disk-b
	- it does NOT know that disk-b has bad sectors where it was
	  good on disk-a
	- it copies all the empty unused space onto the 2nd disk
	  unless you tell it NOT to copy all of the partition
	  in which case you are assuming that you know where all
	  the bits are for a given file/inode tree

have fun

On Fri, 22 Jun 2001, Kwan Wing Keung wrote:

> Dear Netters,
> I want to backup an entire LINUX harddisk to another identical harddisk.
> Some colleagues suggested that I may consider the "dd" command.
> I read the manpage but I can't find any clue.  Any expert advise please?
> Thanks in advance
> W.K. Kwan
> Computer Centre
> University of Hong Kong
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