[CentOS] Re: transfer data from one hard drive to another

Scott Silva ssilva at sgvwater.com
Tue Oct 10 22:14:17 UTC 2006

chrism at imntv.com spake the following on
10/7/2006 5:10 AM:
> Lamar Owen wrote:
>> On Friday 06 October 2006 22:42, Joseph Cheng wrote:
>>> Thx for all the suggestions ppl. I think for simplicity I will either
>>> go with the knoppix & dd solution or I also found ghost 4 unix
>>> http://www.feyrer.de/g4u/
>> I have used the dd solution a number of times, and it works quite well.
>> There are, however, a couple of suggestions I would make:
>> 1.) Use the CentOS rescue mode (boot CD number 1, type 'linux rescue'
>> at the boot prompt) and tell it not to mount your drives.  No need to
>> download Yet Another Linux Distribution to do the work.  Or use the
>> CentOS LiveCD.
>> 2.) While the dd is running, you can check on its progress.  Switch to
>> another virtual console (you are by default on VC 1; hit ALT-F2 to go
>> to VC 2) and send the dd process a SIGUSR1 (run a ps ax and make a
>> note of the dd process's PID; then kill -USR1 $PID); then switch back
>> to VC 1 and you'll see where dd is in your copy.
>> You can then run fdisk or parted and grow the partition; then you can
>> resize the filesystem (I'm fairly certain the rescue mode includes the
>> resizing program; not sure about the LiveCD, but I would think it
>> does).  The native CentOS tools to do this are, in my experience, far
>> superior in quality to the various third party solutions (including
>> Symantec Ghost) availabe to do this sort of thing.  They are a little
>> harder to use, though they seem to work better.
> Interesting.  I wonder if you used this method to copy the image from
> one disk to an identical disk hda-->hdb if you could then unplug hda and
> have the system boot from the "copy" without any other intervention. 
> Kind of like a poor man's RAID1 except you only get back to where you
> were at the instant the snapshot was taken.  I've never tried this since
> RAID cards are so cheap, but I guess I'm wondering out loud if that
> would work.  Anyone tried it?
> Cheers,
If the system was able to boot from the second drive in any other
circumstance, maybe. More likely to work with SCSI than IDE, because scsi is
numbered by their detection, and IDE is numbered by its cable and port
position. But with IDE, you could unplug the first drive and plug the second
drive into the same position as the first (primary master ...). It should boot.
As for raid cards being cheap, software raid works as fast or faster than most
"cheap" raid cards. I mean the less than $200 US priced cards.


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