What is XCP-ng?
A long time ago there was the free hypervisor Xen Cloud Platform - XCP and its commercial version Citrix XenServer. Later Citrix open sourced XenServer, so XCP was no longer needed and discontinued.
But since XenServer 7.3, Citrix removed a lot of features from the free version. The project founder Olivier Lambert wanted to have a free, community based, unrestriced open source hypervisor with the spirit of XCP and so he called his new project
XCP New Generation, in short XCP-ng.
The goal of XCP-ng is to make a fully community backed version of XenServer, without any feature restrictions.
How many network cards (NICs) I need?
One can be enough! However, if you use a network shared storage (iSCSI or NFS), having a dedicated NIC will be really important to get consistent performances.
And if you want to separate your VM network, your storage network and finally your management network, 3 cards will do the trick. A separation between VM network and management is more for convenience than for performances.
Can I use XCP-ng on a USB-Stick (like ESXi)?
No... well... hmm... uhmm... NO!
XCP-ng writes a lot into local files and this writing will wear out your USB-Stick in a short amount of time:
- XAPI: the XenServer API database is changing a lot. Hence writing a lot, and believe me, USB sticks aren't really happy with that on the long run. Note: XAPI DB is what keep tracks on all XCP-ng's "state", and it's replicated on each host (from the slave).
- Logs: XCP-ng is keep a LOT of debug into into logs. For this part however, there is a workaround: use a remote syslog.
(source: comment from Olivier Lambert on the forum: https://xcp-ng.org/forum/post/1915)