What is VMware’s ESXI for
In: Technology
ESX is a Hypervisor
Hypervisors allow you to virtualize operating systems, separating them from the hardware. Essentially you can run multiple Operating Systems on the same hardware at the same time.
Each OS runs as it’s own containerized virtual machine that runs ontop of software pretending to be hardware.
So why would you do this?
For one its much more efficient, instead of running 1 physical server for each OS you can buy 1 more powerful server and share its resources between dozens of virtual machines saving cash on hardware, cooling, and electricity.
VMs are also portable, they don’t care what the underlying hardware is. So you can move a VM from one server to a completely different one without any driver changes.
You can also template servers and deploy new images in minutes without needed to purchase new physical servers every time.
ESX can also failover between servers. So if a server fails the VMs can power up on other piece of hardware automatically.
Similar to how picture in picture separates your television into different screens so you can watch multiple shows at the same time because your screen is so big, ESXi separates your computer into many computers because you have way more hardware than you need.
The benefit is that Windows doesn’t get confused because ESXi tricks it into thinking that it’s running programs by itself, even though ESXi allows many versions of Windows to run different programs on your same hardware than it otherwise could without error.
Let’s say you want to run Linux on your PC, but you still want to keep Windows there in the background.
One way to do this is with a hypervisor like VMware – a bit like a console emulator, but faster and better (because it’s using the same hardware).
The application runs up a ‘virtual machine’, and gives it access to what it thinks are disk drive, ram chips, network card, sound card, etc – but are actually just software services that the software and Windows provide to it. The VM then boots up its own operating system, which thinks it’s running on an actual physical PC – but in actual fact is just an app on your Windows desktop.
This is super-useful – you can create and destroy machines as you see fit, back them up and restore them as easily as any other file, give them to other people, have a bunch of special-purpose machines without worrying about software conflicts, all kinds of stuff.
And if you’re running a whole IT department full of servers, it’s the only way to fly. If one bit of hardware breaks, you can just move the VMs onto a different one, without anyone even noticing. You can buy two great big servers instead of 50 individual ones, and have vastly less maintenance to worry about, plus you can shuffle disk space and RAM around however you want, instead of being tied to the resources available on each individual box. It’s a complete game-changer.
Now, the idea with ESX is that you don’t actually need Windows running on the box that’s hosting the virtual machines. That’s just a waste of resources and more maintenance to worry about.
Instead of having the VMware app on a Windows operating system, with a bunch of VMs inside that, ESX lets you peel off the outer layer. You effectively have the VMWare app running *directly on the bare server hardware* without any OS underneath it.
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