How to duplicate a HD using dd

jdow jdow at earthlink.net
Sat Oct 11 23:33:49 UTC 2003


From: "Willem Riede" <wrrhdev at riede.org>

> Even though the two drives are about the same size, they probably have 
> different geometries (number of cylinders, etc.). That means that the
> partition table that you copied with 'dd' is not going to work.

As long as the second drive is the bigger one this should "survive".

> You may be able to set up partitions manually on your new hd that are 
> no smaller that those on your old drive that have data you need to copy 
> (swap is an example of one you don't want to copy), and then do 'dd' 
> partition by partition (hda1 to hdb1, etc.).

I've had less than happy experiences with this sort of copy operation
on Linux.

> The bs= parameter determines how much gets read from drive one before
> switching over to drive 2 and writing. Too small a size makes 'dd' 
> inefficient. If this is all that you are doing on your PC, you can use
> a good bit of memory, such as 8M (I like powers of 2 -- this is not
> exactly the same size as suggested above, but close).

The size I recommended happens to be one logical cylinder on the disk.
{^_^}





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