Let's say I have two web servers (in a datacenter), A and B. I don't have physical access to any of the servers, only root ssh access.
A is an old server with old hardware, but it's configured the way I want it (security, settings, etc..), while B is a new server with newer hardware (totally different from A), and it has a fresh install of CentOS (for example).
What's the best way to clone server A to server B, so all my files,settings,applications are moved from A to B?
If the newer server runs the same OS version, you could run a simple script from the newer server that copies most of the files:
#!/bin/bash
# Source
SSHSERVER="[email protected]"
SSHPORT="22"
EXCLUDE="/boot/
/lib/modules/
/etc/modules/
/etc/lilo.conf
/etc/fstab
/etc/hostname
/etc/hosts
/etc/mtab
/etc/shadow
/etc/shadow-
/etc/ssh/
/proc/
/dev/
lost+found/
/etc/network/interfaces
/root/
/sys/
/run/
temp/
tmp/
log/"
printf '%s\n' $EXCLUDE > exclude.txt
rsync -avz --exclude-from=exclude.txt -e "ssh -p $SSHPORT" $SSHSERVER:/ /
I used this script in the past to duplicate Debian servers, and it worked fine but some manual (re)configuration, like apt-get install -f was sometimes required. Therefore, use with caution, preferably in a test environment first.
Migrate, do not clone. Different versions, different hardware, evolving best practices will require slightly different configuration.
Spend some effort to create documentation and automation to configure a fresh OS install from scratch. This might be a well-commented script or playbook. Use this to deploy.
If near-identical hardware or VM, that could be a clone. Copy the entire OS disk and re-IP it. You inherit all the quirks of the old install, but it is the same.
