What is the best way to backup (virtual machines, systems state)?

Question

linux

Hello! I need advice and opinions))
You need to organize a server for backups, if you can say "server" that way. Either a normal PC or an old, old super micro 1.8 GHz CPU and 8 GB of RAM. But yes, all right, all the same, only backups will lie there ...
What I want to backup: virtual machines (hyper-v), AD, File server, later sql is possible ...
From Linux machines, only "proxy", the network is mainly on windows and it is logical to install 2012r2 and put everything there. But there is a nuance, perhaps in the future a "smooth" transition of the main servers to linux is planned, but now it turns out that there is an option to practice learning and immediately raise a server for storing backups.
Here, questions and anxiety immediately pour in =)
You can also backup a file file on Ubuntu to a shared folder, but what about virtual machines?
If for example veem-ohm backup? Will she be able to make a backup in the ball?
The state of the system (AD) will also be needed, and in the future, as already mentioned, sql can also be backed up there. But sql is unimportant because the database administrators are engaged in it and I will store a local backup for my own safety.
For practice, I personally would like to try everything on Ubuntu. Is it possible ? Who came across, tell me advice or a link to the manual.
I will be glad to hear your opinion and possible solutions to this problem.
Just in case, let's not store everything in one server, it will be transferred to an external HDD on a weekly basis in order to at least somehow protect yourself.
PS NAS, do not offer a cluster, there is no funding, they said to do it on old pieces of iron, because there is not much data.
Thanks in advance to those who respond!

Answer 1

"back up to a shared folder" is the worst idea I've heard
https://habrahabr.ru/post/239513/
and the client under win https://www.google.com/search?client=ubuntu&channe...