ansible-nas/docs/overview.md

Ansible-NAS currently assumes you know your way around a server. This page is an
overview for absolute NAS beginners so they can decide if it is right for them.

## The big picture

To start off _really_ simple: A NAS ([Network Attached
Storage](https://en.wikipedia.org/wiki/Network-attached_storage)) is a server
mostly for home or other small networks that offers file storage. It's usually a
small box that sits in the corner and runs 24/7. These days, a NAS doesn't just
only handle files, but also offers other services, for instance video streaming
with [Plex](https://www.plex.tv/) or [Emby](https://emby.media/index.html). You
can buy consumer NAS boxes from [various
manifacturers](https://en.wikipedia.org/wiki/List_of_NAS_manufacturers) where
you just have to add the hard drives, or you can configure your own hardware and
use open-source software as the operating system. 

One example of the second variant you'll see mentioned here is
[FreeNAS](https://freenas.org/). It is based on
[FreeBSD](https://www.freebsd.org/), which like Linux belongs to the family of
Unix-like operating systems. One strength of FreeBSD/FreeNAS is that it  
includes the powerful ZFS file system
([OpenZFS](http://www.open-zfs.org/wiki/Main_Page), to be exact).  However, it
does not support the [Docker](https://www.docker.com/) containers the way Linux
does. Also, the Linux ecosystem is larger. On the other hand, very few Linux
distributions include ZFS out of the box because of licensing issues.

Ansible-NAS in its default form attempts to have the best of both worlds by
using Docker on Linux with ZFS. This is possible because the
[Ubuntu](https://www.ubuntu.com/server) Linux distribution supports both
technologies. As the name says, Ansible-NAS uses
[Ansible](https://www.ansible.com/) server automation which is usually deployed
on big multi-machine enterprise systems, not small home servers the size of a
breadbox. 

## Before you take the plunge

The commercial NAS vendors try to make setting up and running a NAS as simple
and painless as possible - for a fee, obviously. The open-source NAS software
providers have lots of resources to help you get started with your own hardware.
FreeNAS for instance comes with extensive documentation, good introductions to
ZFS and other topics, and a large community to lean on. 

With Ansible-NAS, at this point at least, you're pretty much on your own. Though
there is a [Gitter](https://gitter.im/Ansible-NAS/Chat) chat room (see
[support](support.md)), you're expected to have some familiarity with the
technologies involved and be able to set up the basic stuff yourself. 

As a to-do list, before you can even install Ansible-NAS, you'll have to:

1. Choose, buy, configure, and test your own **hardware**. Note that ZFS loves
   RAM - it will run [with 1 GB](https://wiki.freebsd.org/ZFSTuningGuide), but
   it won't be happy. The ZFS on Linux (ZoL) people
   [recommend](https://github.com/zfsonlinux/zfs/wiki/FAQ#hardware-requirements)
   at least 8 GB for best performance, but the more, the better. As robust as
   ZFS is, it assumes the data in memory is correct, so [very bad
   things](http://research.cs.wisc.edu/adsl/Publications/zfs-corruption-fast10.pdf)
   happen to your data if there is memory corruption. For this reason, it is
   [strongly
   recommended](https://github.com/zfsonlinux/zfs/wiki/FAQ#do-i-have-to-use-ecc-memory-for-zfs)
   to use ECC RAM. ZFS also prefers to have the hard drives all to itself. If
   you're paranoid (a good mindset when dealing with servers), you'll probably
   want an uninterruptible power supply (UPS) of some sort as well and SMART
   monitoring for your hard drives. See the [FreeNAS hardware
   requirements](https://freenas.org/hardware-requirements/) as a guideline.

1. Install **Ubuntu Server**, preferably a Long Term Support (LTS) edition such
   as 18.04, and keep it updated. You'll probably want to perform other basic
   setup tasks like hardening SSH and including email notifications. There are
   [various guides](https://devanswers.co/ubuntu-18-04-initial-server-setup/)
   for this, but if you're just getting started, you'll probably need a book.

1. Install **ZFS** and set up storage. This includes creating data sets for
   various parts of the system, some form of automatic snapshot handling, and
   possibly automatic backups to another server or an external hard drive.
   Currently on Linux, it is [something of a
   hassle](https://github.com/zfsonlinux/zfs/wiki/Ubuntu-18.04-Root-on-ZFS) to
   use ZFS on the root file system. If you are completely new to ZFS, expect a
   brutal learning curve. There is a slightly dated (2012) but extensive
   [introduction to ZFS on
   Linux](https://pthree.org/2012/04/17/install-zfs-on-debian-gnulinux/) by
   Aaron Toponce to get you started, or you can watch [this
   video](https://www.youtube.com/watch?v=MsY-BafQgj4) that introduces the
   philosophy and big picture of ZFS.
   
   
After that, you can continue with the actual [installation](installation.md) of
Ansible-NAS.

## How to experiment

The easiest way to take Ansible-NAS for a spin is in a virtual machine, for
instance in [VirtualBox](https://www.virtualbox.org/). You'll want to create
three virtual hard drives for testing: One of the actual NAS, and the two others
to create a mirrored ZFS pool. Note because of the RAM requirements of ZFS,
you might run into problems with a virtual machine, but this will let you
experiment with installing, configuring, and running a complete system.