in short using software like xen and vmware can I have one server with multiple graphic cards and multiple instances of kodi?
I am trying to minimize rack space.
Yes this is possible, but the specifics are probably beyond the scope of a single forum post here. Make sure your cpu supports vt-d for pci/pcie passthrough. Xen/vmware and kvm all support the features you want, which platform you use is going to be a personal choice. I've used esxi and proxmox for years passing through HBA's to virtual machines for NAS duties. I personally prefer and mostly use proxmox now. GPU passthrough is generally more finicky than standard pci passthrough, proxmox specifically will work with many nvidia/amd gpu's but not intel...more info here:
https://pve.proxmox.com/wiki/Pci_passthrough
I would need more information about your exact hardware setup and goals to provide much more help...
I don't have any hardware at the moment.
I want 1 xbmc instance per user so a family of 4 will have 4 gpu's in the one case for example
From each gpu it will go into a hdmi matrix, then out to the tv's. (waiting on hdbaset 2.0)
This way each custom setting will be on that tv. If I go to the garage I can select my instance, move into the bedroom switch from thew garage to my bedroom.
All the servers/stuff will be in racks.
I'm not usually one to discourage overkill rackmount equipment and fun visualization projects but considering you are going to be buying hardware for this to begin with have you considered just buying chromeboxes/raspberry pi 2's/whatever small cheap machines that can handle kodi just fine? I'm happy to help if you are dead set on the central virtualized system (for fun/education/whatever reasons). I just think you may be ahead to consider breaking it up into individual small cheap machines. You can accomplish your software goals with kodi profiles and central mysql databases.
Trust me I have
there are a few things that I have to consider with that setup
1, I am getting all 4k tv's, still a few years off.
2. wall clutter, I hate it. The tv's will be as flat as possible even hidden behind a painting or mirror. Hiding the extra equipment will be an issue.
4. everything is already centralized in one location anyways.
Wow
People get pleasure from WILDLY divergent approaches to achieve the same goal.
I see the beauty in both of their approaches.
intertan's highly engineered approach and minimal aesthetic.
touser's approach to craft a solution using inexpensive components and equipment already on hand.
I'm always conflicted between choosing over-engineering and making do.