[CentOS] A questiong about replacing my failing drive

Sun Jun 12 21:05:26 UTC 2005
Dag Wieers <dag at wieers.com>

On Sun, 12 Jun 2005, Rodrigo Barbosa wrote:

> On Sun, Jun 12, 2005 at 09:16:39AM -0400, Steve Huff wrote:
> > one technique that works quickly and simply for *cloning* disks (i.e.  
> > you've got one disk that's already partitioned, has data on it, etc.  
> > and you've got another of the same make and model, and you want two  
> > exact copies) is to use dd.  since it's a block-level operation, it  
> > couldn't care less about whatever sorts of filesystems you've put on  
> > the disk, it'll preserve the MBR and whatever bootloader you may have  
> > there, and so forth.
> 
> I really don't recomend it. You will get all kinds of geometry related
> problems, not to mention it will take ages to copy.

I don't see why one would have 'all kinds of geometry problems' doing 
this. Except for Windows maybe. Linux doesn't care, the bootloader might.
But restoring the bootloader is trivial.

Also I don't see why it would take ages ? It seems to be pretty 
sequential, it doesn't have any filesystem overhead. And in case you have 
bad blocks it is able to reduce blocksize to recover as much as possible 
(which of course is slower during recovery, there's no alternative though), 
with a filesystem you're pretty much f*cked.

I'm not sure if you ever tried it, but dd (or ddrescue) is much faster 
than what you would normally see as throughput at the filesystem level, 
especialy when you have bad blocks.

--   dag wieers,  dag at wieers.com,  http://dag.wieers.com/   --
[all I want is a warm bed and a kind word and unlimited power]