So I am considering running a cluster with my two laptops and am looking at Proxmox. The problem is I want to know if you can still use the clustered computers running the Proxmox in the Linux / and or another OS. If you could, would it be possible to connect a gaming rig as the master with the two laptops as nodes, with still the ability to run the OS and programs.
Sure thing, I guess the only way is to find out, so I am downloading Proxmox now, hopefully it won't take too long on crappy 1mbps Australian internet :)
Proxmox is an operating system, so you can't install it on top of another Linux system. You can install the repository on debian and install the Proxmox software on top of that. But if you already have Linux installed you can just install libvirt and virt-mamager or whatever virtualisation manager you want to use and cluster that. You'll have to do it manually, I've never tried so I can't tell you how to set it up.
You CAN but obviously in running other programs (especially a desktop environment, which is VERY heavy compared to a CLI-only server) will take away from your CPU horsepower available to VMs. You may also run into problems breaking repositories, as I believe Proxmox uses a custom version of the Debian repos. I've never tried but I'd be interested to see how it turns out.
I second @lessershoe's comment about doing a write up. This would be a cool option for aspiring developers who may only have access to one PC, but want to dabble in networking/OSes/programming/whatnot.
What you are proposing is perfectly possible. You can install a desktop environment to Proxmox (however it is rarely done due to the Web interface).
However, there are several reasons why what you are proposing is not recommended.
The kernel that Proxmox runs on (using the ISO from Proxmox themselves) runs on quite a dated kernel. This is okay if the machine is being interacted with via VM's and Containers as there is no direct access to that low a level. However from a security stand point, the base machine is vulnerable. (Solution: Install Proxmox on top of a newer Kernel through Debian)
Memory. Running additional tasks that KVM/QEMU are not aware of can run you into some pretty damn hilarious RAM issues. The normal pattern happens of when it runs out, it starts to use SWAP, with VM's unaware of this they tend to just stop and crash. Not great.
Master Nodes do not like to be turned off. Building a Proxmox cluster is easy and quite effective to scaling easily. Nodes can be turned on and off as needed with little issues (recommend you use a separate box for storage purposes) with failover of machines in case a node stops responding. However, when the Master node turns off, the cluster (in my experience) gets a little pear shaped. Although the nodes can technically still communicate, they sometimes fail to without the presence of the master, you can get around this by setting a failover master node. Although this can still cause issues when the master node comes back online and the failover master not handing duties back. (a dedicated "heartbeat" network seems to mitigate this issue)
In all, if you want to run Proxmox on your desktop you would be better off setting Proxmox up as the operating system, updating the kernel and using hardware passthrough to a VM that is running your desktop OS of choice. This will mitigate the memory issue and the security of the desktop side of things.
If I were you, I would just set up the two laptops as the cluster. Pick one as the master and leave the desktop out of the loop.
*One major benefit of storing VMs on shared storage is the ability to live-migrate running machines without any downtime, as all nodes in the cluster have direct access to VM disk images.*
This is a nice application. However what I fear is (seeing as they're laptops) that the wired network interfaces are only 10/100Mbit. Resulting in disk speeds lower than that of what a typical laptop drive can do. Although you could easily just use the share to act as a backup location.