I want to setup a VM server and by my previous experience, the first thing that came to my mind was the "VMware ESXi" hypervisor. To use ESXi you need the client application, called "vSphere" to connect and manage your VMs remotely. Unfortunately vSphere is only published for Microsoft Windows and has no Linux version.
So my question is, what alternatives do I have instead of VMware ESXi that provides similar functionality and supports Linux? Are there any free/open-source hypervisors similar to ESX, where they have client applications for both Linux and Windows?
I've also heard from a few people that there is a product based on KVM by RedHat, but I don't have any info on it.
If I were you I'd take a look at Proxmox VE, a free and open source Debian-based Linux virtualization environment like VMware. It can do pretty much the same as VMware. Both the administration and console access to the virtual machines is done from a web GUI. It's production stable - just have a peek at the forums. I've been running a cluster with 10 nodes for 4 years in production and I love it.
To install it go to the Proxmox VE website and download the iso and write it to a USB key UNetbootin or burn it to a disk. You can install it on any standard server/PC preferably with the Virtualization CPU feature enabled.