We have a debian server that is mirrored (RAID1) and wants to replicate everything on the new server. What I was thinking is to take out the disk from the original server and putting it on a second one and add new disks on both server to remirror it back. Now, my question is will this be possible and what are the steps that needs to be taken? I was also wondering if there is a possible way of detecting the new disk without needing for a reboot?

This seems like a really awkward way to replicate a drive. Usually replicating a drive is quite easy, especially if you are using the exact same type of drive.
What kind of drive is it and what do you want to do with it?
To me replicating a drive starts with the dd command, the basis is
The destination (and source for that matter) can both be nearly anything. the if could be "/dev/[your raid array]" or a file or network stream that offers the right kind of data to write to the disk. The of could be a file that holds all the data on a different network location and then on the second server(the new one) you just use the network location as input file(if) and the raid array as output file(of).

The dirty way you are talking about is just bad... it's running the risk of losing everything and I'm not even sure it's easier. Of course you could try it and if your drives are hot swapable you can just remove them and put them back in. http://www.debuntu.org/how-to-rescan...hout-rebooting might help you out on detecting a new drive if it does not automatically is recognised by your raid hardware. If you're using software raid I would like to point you back to my first suggestion.

good luck!

Thanks for your response. I understand your point and its really something I don't want to do. However, the downtime is not generous at all on this server. If they can just give a downtime, I can do a clonezilla or like you said a dd of the drive. And yes the command you stated works like a charm to detect the newly inserted drive.

I'm not sure why you need downtime, if you will just run dd as root and dont write out to the same drive... it shouldn't be too much of a problem to do this live.

Because the drive that I want to copy is the one inserted in the server and is running the OS. I am not sure whether DD will work like this until unless you unmount all fs and boot up a rescue CD to do this.