change harddisk - Further explain of command lines

[Jeff Vian]

Barry Yu wrote:

>
>
> dballester at kernpharma.com wrote:
>
>>Both hd in same machine
>>
>>Suppouse that you wanna 'clone' /dev/hda to /dev/hdb
>>
>>install /dev/hdb
>>
>>Start the machine in single mode and:
>>
>>dd if=/dev/hda of=/dev/hdb
>>
>>Shutdown
>>
>>Extract /dev/hda
>>Insert /dev/hdb in /dev/hda
>>
>>Start machine
>>
>>
>>    
>>
--snip--

>>On Tue, 2004-02-24 at 21:53, kh wrote:
>>  
>>
>>>My current harddisk is running out of space and i'm going to replace it
>>>with something larger, and i want to bring my data with me over to the
>>>new disk.
>>>
>>>It seems that i can use Norton Ghost before on a linux disk, anyone ever
>>>tried this?
>>>
>>>btw i have redhat 8 on that disk.
>>>
>>>kh
>>>    
>>>
>>
>>If you use the latest version of Ghost you will be ok. The only thing
>>that I have found, is that it may affect the Grub MBR contents. All I
>>ended up doing was to boot the install CD then boot into rescue mode and
>>reinstall grub back to the MBR, then I could boot the new drive again
>>with the new partition sizes. Other than that, I found it to work very
>>well. (And also works very quick)
>>
>>Wolf
>>
>>
>>
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>>
>>------------------------------------
>>
> I am not familiar with above commands like : dd , inset and extract,  
> will really appreciate if you could further explain so I can 
> understand how they work.
> Besides, my experience in using the CD booting up in rescue mode also 
> may encounter unexpected problem; After I restored the Ghost image 
> file back to original partition, then booted up Line CD into rescue 
> mode, the rescue process for unknown reason failed to mount this 
> original partition, a message said it has problem, so restore 
> operation failed. It is better to make a boot up floppy with current 
> o/s, in case the the CD rescue mode won't work, this boot up floppy 
> will then be a life saver.
> I also confirm that when used the partimage to make image file out of 
> a partition when my Red Hat 9 installed. I had a successful restore 
> without using CD rescue mode nor boot up floppy, just reboot the 
> machine and everything is up and running fine - making linux image 
> file for restore Ghost can't do that, including ver 8.0 (I  must  use  
> boot up floppy and then do grub-install).

The recommended command above ( dd )   should NOT be used on 2 different 
sized disks.
Although it will copy the first disk to the second, it also will 
overwrite the disk geometry and make the  new larger disk act exactly 
like and the same size as the first smaller disk.  Another problem, 
unless you are copying directly from one drive to another is the wasted 
space int he copy.  It copies byte for byte the source, even if it is 
empty/unused.
-
Another tool I use, besides ghost, is mondoarchive available at 
http://www.microwerks.net/~hugo/index.html.
I have used it via cron for several months, since I saw the article on 
it in Linux Journal (Oct 2003) and it works flawlessly for me to create 
bootable CD or DVD images of my system that will do a restore.
When restoring it allows you to create/resize partitons on the drive 
restored to.  It does not have the problems you will see with dd, and 
also restores the boot loader (grub or lilo) correctly.  I have had no 
problems in restoring to different sized disks.

Mondo is a very good disaster recovery tool and also works extremely 
well for migrating your system to a new disk.