jmtd → hardware → Φόβος

Coolermaster case on the right

Φόβος (phobos) is the name of my NAS, backup and home server. It's the successor to a Mac mini G4 and the (ultimately abandoned) Thecus n2100. It's now on its second mainboard, notes about the first one are at J1900N-D3V.

It's a small (ish) size, passively-cooled PC that I leave on 24/7 and performs various duties for me, most importantly being a large archive storage space and a separate backup space.

Hardware

• Coolermaster Elite 110 case passively cooled
• ASRock J4105-ITX Mini-ITX mainboard with a passively-cooled Celeron SoC
• 2x 4T WD Red drives (one for archive, one for backup)
• 8G RAM (2x4 for dual channel)
• custom ATX PSU blanking plate with DC-DC cut-out from Kustom PCs
• Simtec Entropy Key
• Blinkstick Nano for notifications (see below)

Power consumption

Back-of-the-envelope,

• SoC: 10W (Intel TDP), some people experiencing draw of about 14W idle with one SSD connected

I plan to do some power draw measurements in the near future.

Some notes

The Coolermaster case is high-quality. It's much bigger than I'd like, but is the smallest case I could find at the time. It's about the same size as a HP Microserver (which I was continually recommended when I re-specced this machine) and there's at least growing room.

Front/side USB port provblems

The front (side) USB ports are weird. They are mounted upside down in the case. With two different mainboards I've had a succession of problems using them for removable storage.

Software

Debian GNU/Linux for the operating system. I backup via rdiff-backup.

I don't use RAID (which is not backup).

Remote decryption

I use full-disk encryption which necessitates supplying a passphrase when the machine is booted. Since this is a headless box, some additional work is needed to permit supplying this passphrase over the network. Luckily most of the work is done already by installing the dropbear Debian package and reconfiguring keys and authorized_keys files in /etc/initramfs-tools afterwards. This means I can SSH into the pre-boot environment. From there, I just need to run cryptroot-unlock and supply the decryption passphrase.

Notifications

blinkenlights!

I wanted to add a means of notifying me of events on the machine. I bought a Blinkstick Nano, a tiny USB stick with an LED on each side. I've hooked calls to change the light colour into the success/failure paths for the systemd jobs that drive my backups. Further details here: 1, 2, 3.

The light defaults to off. When an interactive job is in progress, it turns on and blue. When the job completes, the light changes to either green or red depending on success or failure. Green means I am safe to remove the drive, in the case of external drives.

When a non-interactive, scheduled job fails, the light turns red. I usually notice this next morning.