pvc/docs/faq.md

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Frequently Asked Questions about Parallel Virtual Cluster

General Questions

What is it?

PVC is a virtual machine management suite designed around high-availability. It can be considered an alternative to ProxMox, VMWare, Nutanix, and other similar solutions that manage not just the VMs, but the surrounding infrastructure as well.

Why would you make this?

The full story can be found in the about page, but after becoming frustrated by numerous other management tools, I discovered that what I wanted didn't exist as FLOSS software, so I built it myself.

Is PVC right for me?

PVC might be right for you if your requirements are:

  1. You need KVM-based VMs.
  2. You want management of storage and networking (a.k.a. "batteries-included") in the same tool.
  3. You want hypervisor-level redundancy, able to tolerate hypervisor downtime seamlessly, for all elements of the stack.

I built PVC for my homelab first, found a perfect usecase with my employer, and think it might be useful to you too.

Is 3 hypervisor really the minimum?

For a redundant cluster, yes. PVC requires a majority quorum for several subsystems, and the smallest possible majority quorum is 2/3. That said, you can run PVC on a single node for testing/lab purposes without host-level reundancy.

Feature Questions

Does PVC support Docker/Kubernetes/LXC/etc.

No. PVC supports only KVM VMs. To run Docker containers, etc., you would need to run a VM which then runs your containers.

Does PVC have a WebUI?

Not yet. Right now, PVC management is done almost exclusively with an API and the included CLI interface to that API. A WebUI could and likely will be built in the future, but I'm not a frontend developer.

Storage Questions

Can I use RAID-5 with PVC?

The short answer is no. The long answer is: Ceph, the storage backend used by PVC, does support "erasure coded" pools which implement a RAID-5-like functionality. PVC does not support this for several reasons. If you use PVC, you must accept at the very least a 2x storage penalty, and for true safety and resiliency a 3x storage penalty, for VM storage. This is a trade-off of the architecture.

Can I use spinning HDDs with PVC?

You can, but you won't like the results. SSDs are effectively required to obtain any sort of reasonable performance when running multiple VMs. Ideally, datacentre-grade SSDs as well, due to their significantly increased write endurance.

What Ceph version does PVC use?

PVC requires Ceph 14.x (Nautilus). The official PVC repository includes Ceph 14.2.8. Debian Buster by default includes only 12.x (Luminous).