As Wednesday is very fond of reminding Uncle Fester, “if you Build in haste, you will repent at leisure”.
So, for example:
You might buy unsuitable hardware
You might buy expensive hardware that you don't need and will never use
You might have hardware that has been damaged in transit and will fail soon after you start using it for real
You might configure your hardware incorrectly
You might fail to configure vital settings that will avoid your data being irrevocably lost
You might fail to ensure that when hardware does go wrong in a non-destructive way that it can be fixed successfully without losing your data
When we were writing this guide we came to the conclusion that it was impossible to achieve all of the following:
Be comprehensive and detailed - cover all the bases and provide enough information to help you achieve everything needed to create your TrueNAS server
Keep it short and simple and easy to understand without being over technical - so that you don't get put off reading this, and you don't reach the end of your natural days and join the Addams family in actual spirit rather than metaphorical spirit
As you will see as you read through this guide, TrueNAS delivers a range of different types of functionality, each of which has quite a lot of settings for functionality, security and performance - in other words it is quite technical[1], and that is why we cannot achieve both of these objectives - but we hope that we have done our best to explain things simple and avoid too much technicalities whilst still giving you the breadth and depth you need to be successful.
As a consequence this wiki doesn't just cover the technicalities of building and configuring your server, it also spends (what you might naively believe is an inordinate and unnecessarily) large amount of time and detail on:
Planning - before you buy or build anything - so you don't go down any blind alleys or make irrevocable but incorrect decisions that will plague you forever afterwards;
Configuring - after you have built and before you test - so that it is genuinely resilient/redundant and manageable
Testing - after you have bought and built but before you start using to store any data that you cannot afford to lose - so that you prevent avoidable early issues and are ready for issues that arise due to wear and tear and the passage of time.