System Cloning

[griffinmt]

Given that I have a system that is configured and ready to use, is it possible to 'clone' it onto a similar system (some hardware differences) without having to spend the time building it from scratch and risk making typos/taking different options etc.

[Mikko]

Yes. There are specific tools for this, but it can be done simply with tar or rsync.

I've often done approximately the following

- boot the target machine from live cd

- partition and mkfs as needed

- mount the root partition and cd into it

- rsync (options -a and -H, at least) over the network from an existing system the following directories: bin dev lib sbin selinux usr boot etc opt root srv var

- mkdir the following: misc net proc sys home media mnt tmp (assuming you want an empty /home)

- chmod 1777 tmp

- delete /etc/ssh/*key* and /etc/udev/rules.d/*persistent* files; they will be regenerated

- edit /boot/grub.conf and /etc/fstab to point to the correct partitions; 'blkid' is your friend if you use UUIDs

- possibly edit /etc/sysconfig/network and the contents of network-scripts, if static ip is needed

- run grub and do 'root (hdX,Y)' and 'setup (hdX)' with appropriate drive X and partition Y

The system should then boot (unless I forgot something essential ). It's very easy to make a silly mistake in grub.conf or fstab such that you need to boot from the live cd again and fix them in order to get the system to boot. Also, doing the above will clone user accounts but not /home. Of course, you can create a tarball and drop that into multiple machines instead of using rsync. You just need to take care to preserve permissions and hard links. Regardless, transferring the system over a 100 mbit or a gbit ethernet only takes a couple of minutes and is almost certainly much faster than running the installer.

Hardware configuration is usually not a problem. You may want to delete the cloned xorg.conf if you have one. In my experience everything else has just worked (so long as the persistent udev rules from the source installation are removed).

If you don't have an ethernet switch, you can still connect the machines directly to each other with a regular ethernet cable. Current hardware will automatically negotiate a straight ethernet connection. Then just stop NetworkManager on both machines and set ip addresses and routes manually.

[griffinmt]

Thanks for that info.

I did not mention that I might want to do this without a network active between systems.

Therefore I am looking for something that can be built onto one or more DVDs, taken to the remote system, boot from the DVD and have it do the job semi-automatically.

If I know these are all single disk setups with a single root partition and one swap partition and a single ethernet using DHCP, Then the only 'real' variable is the hostname, plus additional user account(s).

That being said, could this be scripted on the DVD such that someone else could insert and boot the DVD, answer a few questions and then have it complete?

TIA,

[Mikko]

Originally Posted by griffinmt

If I know these are all single disk setups with a single root partition and one swap partition and a single ethernet using DHCP, Then the only 'real' variable is the hostname, plus additional user account(s).

I think you can actually set the hostname to localhost.localdomain in /etc/sysconfig/network and then use dhcp and the hostname will be set automatically.

Originally Posted by griffinmt

That being said, could this be scripted on the DVD such that someone else could insert and boot the DVD, answer a few questions and then have it complete?

Sure, but there is probably some trial and error before you get a working DVD, and you end up burning and test-booting a few more DVDs than you'd like. If the machines can boot from a thumb drive, then that would be a much less painful way to do it since you can easily edit the contents of the thumb drive. Even if they can't boot, I'd still probably boot from a standard live cd and put the system image and the installation script on a thumb drive. I think your users would be able to run a script from a thumb drive?

If you actually have a homogenous set of machines with identical partitioning, you might be able to use one of the cloning tools. Try googling. There are several, many of them created for cloning compute clusters. It's been many years since I looked at them, so I can't really give pointers. Then there's Red Hat's Kickstart, which I've found thoroughly useless, but I haven't tried it in several years. Then again it's not very difficult to write your own script to clone a set of (nearly) identical machines. I've always worked with a bunch of very different machines with different partitioning schemes, so it's been less trouble to do the syncing and fstab editing manually than to try to force one of the existing automatic tools to do something different for each machine.

[griffinmt]

Thanks.

I'll do some tinkering based upon the info you provided. I don't mind the extra work with the DVD etc if I am learning something in the process. And this is only for 3-4 systems.