I have a Mac Mini late 2012, 16GB ram with 500GB disk, multiple (3) gigabit NICs, and some external USB3.0 drives.

My requirements for guest OS are:

  • One Macos High Sierra with Server.app
  • One pfSense linux guest (requirements are minuscule. CPU 600MHz, 512MB RAM, and 4GB HDD)
  • Maybe a second Linux instance to tool around with - No windows guest VM

My research shows I don't need to use ESXi but it has a lot of features I'd like to leverage, snapshots, Multiple test configurations and etc. Given that nothing else is running in the ESXi environment.

(the goal of knowing how to measure this lets me weigh if I upgrade to an SSD and or even bother to install ESXi)

I'll be using the ESXi6.7

Spec of the hardware, 16Gb Ram 500GB HDD or SSD

In your experience, how much (CPU/RAM) overhead would the virtualization layer add?

  • Welcome to Ask Different. Just a quick observation; the question, as written, has few problems which makes it off topic: pfSense on a VM (opinion based) in OS X, a benefit of OSX versus ESX (opinion), and finally ESX overhead of OSX (too broad). Please rework the question so there is one distinct question which can be answered. For more info, please see How To Ask in our Help Center
    – Allan
    Aug 22, 2018 at 19:48
  • That said...at it's core there's some good questions here, it just needs to be refined. For example, have you tried installing ESX and lighting up a pfSense VM? What was the results? Also OSX overhead in ESX...what's the sizing of the VMs? What resources have you allocated? There's lots of details that need to be supplied so we can begin to speculate.
    – Allan
    Aug 22, 2018 at 19:51
  • Ok, I don't know enough about the technologies I'm asking about and using. I'll try to rephrase.
    – Sunil
    Aug 24, 2018 at 20:30
  • Ok, do I need to resubmit or something? Sorry really new here.
    – Sunil
    Aug 24, 2018 at 21:00
  • If you edit the question it will go on the review for reopening queue where it can be looked at and if enough people think it is a good question it will get reopened - however I think you have not improved it enough see Allan;s comment - also you comment "I don't know enough about the technologies" implies to me yopu need to read more about them
    – mmmmmm
    Aug 24, 2018 at 21:31

2 Answers 2


Decided to go with VMware, more an industry standard. Looking into my own question, the overhead for VMware outweighs the the benefits. I put it at about 15-20% on CPU & RAM. This is from research, not empirical data. I have several devices/servers I want to build, none are resource intensive. I upped the Mac Mini to 16gb Ram 1TB SSD and 2TB SSHD. The max it can take for less than $200. Should be plenty powerful.

Some context... This is more of a home project. A server to store family's media, documents, and backups (mostly macs & iOS). I'll also build a full featured network firewall, I don't like black box or desktop firewalls. I like to know what's going on. Lastly a home automation server, there are some integrations between devices/protocols that require a system in the middle.

I used to be an Windows engineer, 20+ years ago, when that was a new thing. Since then moved on to management. I try to stay close to the technology, but virtualization (hand's on is new to me). Tired of the planning and managing tech. I'm not allow to touch anything anymore. I have to use my own desktop teams for my work machine. I want to get my hands back on. Hence this home project. though a home project, it seriuos for me, I like to research and understand best practices. Not to mention the geek out factor. :-)

Look forward to learning here and other sites. Who know, this "old man" (not talking punch cards or anything, may be able to answer some questions.

Thank for your help.


  • There is the free Parallels vm that runs macOS and Linux. It will not run Windows unless you pay up. You can use the free Oracle virtual box to run Windows. Just do it. Jan 2, 2019 at 6:05
  • With Parallels 13, I was running macOS in a VM. I started a second VM with macOS that needed to boot. Both VM slowed way down. After everything got running in the second VM, I could do minimal work, but it was painful. FYI. Jan 2, 2019 at 20:39

In my experience - you have to just commit. If you think you need or could use the ESXi features - you should back up all your data and then wipe the hardware and run ESXi.

There's nothing as powerful or capable if you try and run virtualization on top of the MacOS host OS. You have far more resource loss there and far less flexibility. If you are going to virtualize, there's almost no case where ESX is more overhead or less performance than another solution.

The only question is do you want to invest the time to set that up. With power comes pain and learning and complexity. If your time to learn is billable or improves your happiness or ability to seek employment - all the time you invest learning ESXi is a return on investment. If you don't care to learn or have too many other things you need to do - hire out that to someone at a lower wage than you or just run things in the cloud somewhere or handle multiple hardware. You can virtualize on an Intel NUC far cheaper than you can on Mac hardware.

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