Full clone of running Linux Server (Centos7)

Nitup · 09-14-2017, 11:01 PM

I need to create a completely identical linux system on another machine.

Now I have a linux server up and running with Centos 7 installed. It acts as a server for some web resource. Also it runs in a KVM virtual machine. So I have no chance to boot from a livecd anyway.

I can't stop my system as well, only for a couple of minutes, but this won't help anyway.

So my question is how to create a complete clone of running system.

I have the following disk layout

Code:

/dev/mapper/VG-lv_root 100492376 21506376  73858220  23% /
devtmpfs                 1930476        0   1930476   0% /dev
tmpfs                    1941024        0   1941024   0% /dev/shm
tmpfs                    1941024    57980   1883044   3% /run
tmpfs                    1941024        0   1941024   0% /sys/fs/cgroup
/dev/sda1                 499656   201976    271468  43% /boot
overlay                100492376 21506376  73858220  23% /var/lib/docker/overlay/2a5e41fa94f64ffefaaa4a644cb8413e1579d877e35187bae2cf38772acbdb1a/merged
shm                        65536        0     65536   0% /var/lib/docker/containers/5c831624ff9e4d0dbcdf73120df94a601f0a29cb34716d5c7906ef29d778c938/shm
overlay                100492376 21506376  73858220  23% /var/lib/docker/overlay/3d904f042dc29ac06871cd301b89c4c8fadd254fe24855369279b5df0343968c/merged
shm                        65536        0     65536   0% /var/lib/docker/containers/e20b5a4bcce42d6a8d33ae7e66e33150782960b60babf65d699c52c4ba7ae24f/shm
tmpfs                     388208        0    388208   0% /run/user/0
tmpfs                     388208        0    388208   0% /run/user/1001

I want to clone this system into another machine that is a KVM as well. I am running Proxmox on my home server. So I have any kind of access to this machine.

Please suggest how to create a complete clone in this case ?

Thanks

TenTenths · 09-15-2017, 03:52 AM

If it's a virtual machine then just take a snapshot of the machine and clone it from the snapshot.

Nitup · 09-15-2017, 08:50 AM

I cannot create a snapshot as far as I don't have access to the hypervisor, I am using VPS hosting and have only access via SSH/VNC.

Could you suggest the best choice in this instance.

jlinkels · 09-15-2017, 09:02 AM

Install a new machine with Centos 7. Make sure your GRUB and kernel are identical. If you use the same installation as the original machine and you did not upgrade the original machine this will be the case.
Install rsync on both original and copy if it is not installed yet.
Make sure your copy will boot and has SSH root access.

Rsync the original machine to the new machine:
rsync -av --exclude='/proc' --exclude='/sys' / ip.copy.machine:/
Issue this command as root from the original machine.
Doublecheck if you are on the original and doublecheck the command line. The source '/' must come before the destination 'ip.copy.machine:/'.

After copy is complete, on the copy find in the udev config directory 70-persistent-net.rules and delete the line describing you primary network interface. It will be recreated. I don't know what the udev config directory is in Centos.

If fstab uses uuid to mount volumes, check the uuid of the volumes on the copy using blkid. If the uuid's are different, edit fstab to create the correct devices to mount.

When this is done, reboot the copy.

If you have databases running on the original, either stop the database. Or make a database dump before the rsync action. After the copy is up and running, restore the database from the dump.

jlinkels