I have used Proxmox as my main hypervisor since 2016 and even after trying out others have always gone back to it. I suspect that part of it is just that I’m familiar with it now, but why did I choose it in the first place?
I tried a few hypervisors before settling on Proxmox and for me, it was the best balance of ease of use and performance out of the “free” hypervisors. I did run a Xen based hypervisor for about 6 months before I switched to Proxmox but I never really felt at home with it although I can understand why so many people do use it. ESXi is quite restrictive without a paid license and a lot of the features used in the Enterprise are missing from the free version. I tried Hyper-V and ran that for a few months and like ESXi I found it to be pretty good for running virtual machines but Proxmox provides me with virtual machines, containers and a web based GUI all neatly integrated. I could almost certainly get similar performance levels by just installing a Linux distribution and running kvm for the virtual machines and using lxc or Docker for the containers but the Proxmox GUI makes life easy for the majority of tasks.
I feel at home with a Unix like operating system (my career path from junior tech support to Backup specialist included Unix technical support, mainly HP-UX and Solaris, along the way) so I’m not scared of the command line, but the GUI definitely makes life easier. This also means that if there’s issues I stand a good chance of being able to troubleshoot as Proxmox is essentially a tweaked Debian Linux under the hood . There’s no limitation on the features either with Proxmox; if I had the equipment (and was prepared to pay the electricity bill) I could run a multi-node Proxmox cluster without having to pay any license costs.
Proxmox containers are lxc, not Docker which has taken the world by storm over the last few years, earlier versions used OpenVZ and as most of the services I’m using at home can run on Linux I can run the majority of them in an lxc container without the added overhead of requiring a complete virtual machine. Until recently this was how I ran things but since I started playing with docker containers I have migrated the majority of services over to docker containers on the NAS server itself.
I also found that for the few Windows virtual machines I use, the performance is better under KVM than under Xen. Obviously, this may have changed over the last few years but I’m more than happy with the performance I’m getting from Proxmox and don't feel the need to try Xen, ESXi or Hyper-V again. I will be honest though, if I was running mostly Windows virtual machines and not many containers (or even Windows containers rather than Linux) I’d seriously consider Hyper-V.
The Proxmox web interface provides me an easy way to create Virtual machines and containers and I rarely need to drop down to the command line and the few issues I’ve had in the past have usually been resolved with a quick Google search which usually points me to the Proxmox community forums where someone else has discovered how to fix the issue. I have noticed that Proxmox staff will often provide assistance on the forums which I think is a fantastic way to treat your users, even if they aren’t paying the license fee for the full blown support.
There are some issues with Proxmox, mainly to do with the fact that it’s not as popular as Hyper-V or ESX in the enterprise space; for example, backups of virtual machines. Hyper-V and ESXi (paid version) are spoilt for choice, all the mainstream backup vendors support them and some even provide free versions of their software that allow you to back up a limited number of virtual machines for no cost. None of the mainstream vendors support Proxmox although you could install backup agents and do traditional agent based backups. Proxmox backups, until recently, are basically a dump of the entire virtual machine or container and unless you powered it down first was effectively a crash consistent backup of the running machine. Proxmox have released a backup system, but as of yet I’ve not tried it, when I do, I’ll be sure to write about it on here.
