Q: Mini configuration for os x server

Which year model Mac Mini....? see > How to identify Mac mini models - Apple Support

The RAM including dual drive setups can easily be be done in the 2010, 2011 and 2012 unibody models, where only the drive can be upgraded in the latest model. see > http://eshop.macsales.com/shop/mac-mini/

If you are buying new or used or refurbished, a few things I suggest for use in a

commercial environment:

-If you are purchasing a new Mini, order it with 16 GB of RAM and a smaller SSD.

If you are purchasing a used or refurbished 2012 0r earlier, upgrade to 16 GB RAM

and an internal SSD.  The main reason for the SSD is long term reliability (no moving parts).

The suggestion for 16 GB of RAM is to allow multiple services to be run simultaneously

and room to expand additional services later.

-Install only the OS, Server, an any additional software required to deliver or manage

the services that your Sever will provide.

-On 2011 or later Mini models, I suggest getting multi drive Thunderbolt enclosures

(OWC has quite a nice selection of them).  They can be set up in RAID configurations

as mirrored drives (redundant) so there will always be a backup. I suggest Thunderbolt

for reasons of speed.  On 2012 or later Minis, you can make use of USB 3.0 drives instead of

Thunderbolt. 

Which ever external drive route is taken, that is where you will store all of your data.  Reason for this

for ease of replacement and redundancy.  If a drive dies, you would simply switch to the backup,

unplug the faulty drive and replace and restore the data to it.