The following is a list of all the essential components of the Dramble, along with some links to the places where I purchased them:
|Raspberry Pi 4 Model B||4||$45||To run Drupal.|
|8A 4-port USB charger||1||$19.99||Provide adequate power for the Dramble.|
|6-pack micro USB cables||1||$9.99||Connect the charger to the Pis.|
|Samsung EVO+ 32GB microSD card||4||$8.60||Storage for each Pi.1|
|8-port unmanaged Gigabit network switch||1||$29.99||To build a high-speed private network.|
|Raspberry Pi 'Dog Bone' Stackable Case||1||$28.99||To hold the Pis.|
|14" Black Tactical Weatherproof Case||1||$24.99||To make the entire setup transportable.|
1 Why use a more expensive card like the Samsung EVO+ when any old microSD card would suffice? Well, the microSD card you use can have a huge impact on the overall performance of the cluster—especially for applications that need fast small-file random write performance, like MySQL! Read microSD Card Benchmarks page for more.
2019 Edition - PoE and Blinksticks
For the latest edition of the stack, since the Raspberry Pi foundation released an official PoE HAT, I decided to splurge a little and convert the entire cluster to PoE, so I could save hauling around two independent power supplies. This also necessitated me buying Blinksticks since the Pi GPIO header was consumed up by the HAT and my LED boards would not fit in my case anymore with an extended header.
|Blinkstick Nano||4||$19.84||Status indicator LEDs for each Pi.|
|55W 4xPoE 5-port Gigabit network switch||1||$59.99||PoE allows me to lug one less PSU.|
|Raspberry Pi PoE HAT||4||$20.00||So the Pis can be powered by the switch.|
|10-pack of 6" Cat6 network cables||1||$13.98||Slightly nicer patch cables.|
None of the 2019 edition accessories are required to run your own cluster, however—they're just nice add-ons that make the cluster's fit and finish a bit cleaner.