Docker Swarm : Raspberry Pi powered

Architecture

• 1 RPi 4 4GB (Yggdrasil)
• 2 RPi 3B+ 1GB (Thor & Loki)
• 1 RPi 3B 1GB (Odin)

Performance tests and consequences

SD Card speed

SD Card used : Samsung Evo Plus 32G

	RPi 4	RPi 3B+	RPi 3B
Seq Write Speed (1000 MiB)	18 MiB/s	16 MiB/s	1 MiB/s
Seq Read Speed (1000 MiB)	40 MiB/s	20 MiB/s	19 MiB/s

RPi 3B is insanely slow on seq. write speed. Might be an hardware issue !

Disk speed (USB)

Disk used : Seagate 1 To Expansion USB 3.0

Disk format : NTFS	RPi 4	RPi 3B
Seq Write Speed (1000 MiB)	18 MiB/s	18 MiB/s
Seq Read Speed (1000 MiB)	63 MiB/s	29 MiB/s

Disk format : Ext4	RPi 4	RPi 3B
Seq Write Speed (1000 MiB)	85 MiB/s	Not tested
Seq Read Speed (1000 MiB)	106 MiB/s	No tested

I need high speed between HDD <-> Pi <-> Ethernet, so try to reduce bottleneck.

Disk speed (NFS)

Drive is on RPi4, NFS mounted on other Pi.

	RPi 4	RPi 3B+	RPi 3B
Seq Write Speed (1000 MiB)	--	30 MiB/s	11 MiB/s
Seq Read Speed (1000 MiB)	--	40 MiB/s	11 MiB/s

RPi3 Ethernet port is 100 Mbps which is ~11MiB/s so this is accurate.

Ethernet speed

	RPi 4	RPi 3B+	RPi 3B
Download	35-88 MiB/s	18-30 MiB/s	11 MiB/s
Upload	? 0.5 MiB/s ?	16.7-24.5 MiB/s	10.4 MiB/s

Pre-requisites

DietPi

Install DietPi OS on every Pi following this tutorial.

Configure SSH Keys

On each RPi :

1. Generate RSA keys ssh-keygen
2. Copy the output to ~/.ssh/authorized_keys on every other Pi
3. Install Docker with dietpi-software : sudo dietpi-software