DD not working--SUCCESS!

[Karl Larsen]

Jacques B. wrote:
>> No, you're taking bytes off and putting them on drives.  Neither drive
>> should be mounted.
>>
>> Matt Flaschen
>>     
>
> Further to this, dd is a powerful utility that allows you to write
> directly to a device.  Whereas cp, rsync, and other such commands
> require a mounted file system.  dd copies from one drive to the other,
> oblivious to the actual content.  Just that byte 1 on /dev/sda5 is
> \x65, so write \x65 to byte 1 on /dev/sdb6.  Byte 2 on /dev/sda5 is
> \x80, so write \x80 to byte 2 on /dev/sdb6.  All this happens at the
> physical layer.  Whereas cp for example will look at the information
> in the inode to determine where to find the file, and how many bytes
> to copy so it requires a file system in order to work.
>
> Even though a drive is not mounted, so long as it is connected
> properly dd can read/write to it.  Because it is doing so at the
> physical layer...
>
> I realize there may be some information overload going on here.  But
> hopefully my analogy of photocopying the book illustrates the danger
> of dd'ing a live system.  In some scenarios that would have to be done
> (computer forensic investigation of a server that cannot be taken down
> for example).  But not in your scenario. Picture a mechanic trying to
> work on an engine that is running.  Now imagine trying to rebuild that
> engine while it's running.  In the case of copying an entire operating
> system and user files as you are doing, dd is rebuilding a complexe
> system (granted using a very simple process).  That cannot be done
> with any assurance that it will work properly if the system being
> copied is running hence in a state of constant change.  It's not like
> using rsync or other such tools that work at the file system level and
> will place a lock on a file when doing something with it so that it
> cannot be changed while it is copying it.
>
> If after everything everybody has told you you still do not consider
> dd'ing a live system as a poor and risky practice then nobody will
> ever convince you.
>
> Jacques B.
>
>   
    I of course see what your saying. It would be best if you have a 
computer dedicated to running dd. You plug in 2 hard drives and boot up 
hoping bios takes care of the hard drives :-)

    On the computer you say dd if=hd1 of=hd2 and neither Hard Drive is 
doing anything else.

    But I don't have that many computers and hard drives. So I do what I 
can and it appears to have worked.

-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.