Linux – Best way to clone a live linux system

I've been doing P2V conversions with Vmware converter and V2P conversions (with Acronis True Image) for two years.It works, even if Vmware Converter is kind of slow and Acronis often makes the resulting system unbootable because of the grub and because the partitions are wrongly mapped in /etc/fstab (so you have to boot with an bootable linux and fix grub and /etc/fstab). There is no easy solution for P2V conversion because the devices can get wrongly mapped in the new setup. Exactly in this point Vmware Converter does a great job,even if it sometimes fails for stupid reasons (if you have partitions greater than 100 GB, there are chances the conversion will fail because formating 100 GB takes a long time and the Converter takes a period of longer then 5 minutes without output as a sign of failure).

You're missing an important piece of information here - which virtualisation hypervisor?

If it's VMWare there are both free, limited and paid, more-powerful, P2V convertors available that can create VMs native to VMWare or to the .OVA open virtual machine format.

Others will know the P2V conversion options for Hyper-V/KVM/Xen etc. better than I.