Mobile “off-grid” Data Center
February 1, 2020
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Molly contains a little more computing power than typical in an overland expedition vehicle. This little luxury makes it easy for us to use our laptops, ipads and iphones in seamless coordination with the electronics in Molly. There are three major components in Molly’s house, compute, storage and networking. The very same building blocks found in a data center.

In our last “around the world” trip, we had lot’s of issues with little hard drives that continuously failed and risked us losing treasured photos. This caused a little too much stress and countless wasted hours backing up photos. And we lost some photos, so we wanted to do things differently this time. We added a solid wifi network to make local device to device communication easy, and ideally to connect to hotspots or cellular networks when they are available. We are also seriously into maps, and the fixed computer tracks us so we don’t have to worry about tracking ourselves.

The setup is a little complex, but hidden in this complexity is simplicity for us in our day-to-day travels. Here are the details.

Storage

As mentioned, we have had terrible luck in the past with reliable storage. So, this time we installed Solid State Disks (or SSDs) over more traditional Hard Disk Drives (or HDDs). Mainly because there are no moving parts in SSDs and tolerate the bumpy rods better. Other advantages

  • Draw less power, about 2 to 3 watts per disk than 6 to 7 watts for HDDs
  • Are faster with read and writes of 550MB/s and 520MB/s, respectively than 50 to 120MB/s for HDDs
  • Need less cooler and fans, because each disk uses less power.
  • And are quieter, with no no spinning disks and smaller fans.

Ultimately we just picked them because they are more reliable. And we increased the reliability by placing them in a NAS (or Network attached Storage) unit which allows for RAID (or Redundant Array of Inexpensive Disks). This is obviously a little ironic, as these disks are anything but cheap. In fact SSDs are typically 5 times more expensive per gigabyte than HDDs. Our setup

  • Four Samsung SSD 860 EVO 2TB 2.5 Inch SATA III Internal SSD (MZ-76E2T0B/AM))
  • Installed into a Synology DS416slim NAS
  • Running RAIS level 5, meaning we can tolerate complete failure of one of the four drives and not lose any data.
Sold State Drive we use
Network Attached Storage unit.

The NAS comes with a built in operating system and file management utilities. And Synology has lots of features, like automatically backing up our laptops, can stream movies and music to our projector and ipads/iphones and when connected to the internet, will backup our photos and files to another Synology device located in our home. It is an all-rounf serious little device.

Fortunately the DS416slim works off 12 volts, so is compatible with of house voltage. It consumes around 17 watts when in use and 11 watts when idle. We placed a little voltage stabilizer between the house battery and the NAS, just to make sure it always gets 12 volts, even if the house batteries are a little low. The NAS is hidden in our electrical cabinet; out of sight and out of mind.

Compute

For our computer is decided on the Mintbox Mini 2 Pro from Compulab. This is semi industrial fan-less computer with ports for just about anything. It is running a linux Tara operating system.

Everything we do with this computer we could do with our laptops, but it does it much more conveniently. No need to plug in cables or power it up for a task, as it is permanently connected to other devices and is always on. Like the NAS, it is securely bolted down in our electrical cabinet.

It is a general purpose computer, so it can do just about anything, but for us it mainly does things related to tracking, mapping and blogging. But more on that later.

This computer is 112 mm X 84 mm X 34 mm, weighs just 350 grams, consumes 5 to 15 watts with an operating voltage of 7 to 20 volts. It is hard wired into the NAS and the Cradlepoint modem, so we removed the wifi antennas. The power comes directly and unregulated from the house battery, but is fused.

Networking

No expense was spared on networking equipment, with an industrial grade network router and modem from Cradlepoint. This provides our local wired and wifi network and can also connect to external wifi and cellular networks for Internet. This is the networking glue between storage, the computer and all our other wifi devices. It is also , securely bolted down in our electrical cabinet.

Cradlepoint COR IBR900 600M with extensibility dock

The Cradlepoint COR IBR900 600M connects to the computer and NAS, but is also connected to Molly’s engine management system via the OBD-II port and a series of serial cables and adaptors based on the OBD-II Adaptor kit from Cradlepoint. We mounted a 5-in-1antenna on the back of Molly. This antenna has five elements, including GPS/GNSS, 4GLTE/3G/2G 2xMIMO and Wi-Fi 2xMIMO.

Why all of this Stuff

We ate still working through what we will use this gear for. Here is a little more details on how we use this gear.

  • GPS Tracking Software. We installed is Traccar which is an open source GPS tracking platform. We had to write some extra code so Traccar could understand the GPS and engine management messages coming from the Cradlepoint modem and the GPS messages coming from the ID-5100A HAM radio. This software allows us to continuously track our location and store the tracking files to our computer. The GPS antenna is located on the back of the truck, and gets a pretty good view of the sky, even when under a forest canopy or in a canyon. We also had to change the software to make sure it could operate without an internet connection. But most importantly, now that it is setup, it is a zero effort to operate the system, with it quietly logging track and one less thing for us to worry about.
  • Map Tile Server. The Traccar software requires a map, which is typically accessed on-line from the Internet. But obviously when we are in the middle of nowhere, there is no Internet. And we love our maps. So we installed our own map server, technically called a Map Tile Server. This server allowing us to bring up a detailed map for any place in the world. We use a base-map from Open Street Maps and open source software form Open Tile Maps. This solution is good, but not great, and really only allows us to view a very large collection of very detailed maps, but that’s about it. So our iPads also have maps, and more features for route planning and tracking.
  • Blogging with WordPress. The most useful feature the computer provides is being able to edit our blog while away from the internet. We have a full WordPress installation and a mirrored copy of our blog. We can create blog entries off-line and when we get into Internet coverage, can sync this entries with a single click of a button.
  • Backing up Files. We haven’t really sorted this out yet, but the plan is to have a simple seamless or 1-click backup solution. When we are out taking photos and return, we just want these photos to be backed up. Some for our laptops, they should be doing an hourly Time Machine backup automatically. The ultimate dream will be for the NAS to automatically back itself up to a remote NAS, whenever Molly stays into Internet coverage. This is certainly a feature of our NAS, it just needs to be configured.
  • Music and Movies. The NAS houses a copy of our music and movie collection. The NAS has a built in media server, allowing our laptops, iPhones, iPads and even our movie projector to connect to play music and movie files.