This guide is a step-by-step process on how to migrate VM's from SolusVM or Virtualizor using KVM to Proxmox.
1.) Find the server in SolusVM, and also have the corresponding service open in WHMCS
2.) Make a note of the exact specifications of the server, including the IP addresses, disk size, RAM and CPU sizes / count. Also, make a note of the 'ID' which will allow you to find the correct logical volume in LVM.
3.) Change the service in WHMCS from 'VPS' (SolusVM) to 'Cloud Server - UK London', and populate the 'configurable option' fields to match the VPS specification found in the previous step.
4.) Click 'Create' in WHMCS to provision the VPS and check that the VM is created successfully (it will take around 2 minutes for the VM to fully complete and will start automatically once done).
5.) Shutdown the machine on both Solus / Virtualizor, and Proxmox to ensure the disk copies in a consistent state.
6.) SSH to the 'destination' server, and run the following...
ssh firstname.lastname@example.org -p 22 "dd if=/dev/from_lvm" | dd of=/dev/to_lvm
7.) Once the dd has completed, the data has been copied to the shutdown disk on the destination server (or, 'to_lvm').
8.) Boot the VM up from Proxmox / WHMCS and ensure that the server boots to the login prompt, and also ensure the server responds to ping through the serial console.
9.) Remove the VM from ONLY WHEN YOU ARE 100% SURE OF THE ABOVE.