Kubernetes Cluster on Raspberry Pi – Persistent Storage Hardware

26 Apr 2019 by Lior Kamrat

Took me a while but I am ready to continue with this series. In the previous post, I touched a bit on the local, Micro SD storage of the Pi’s but for this is not enough when it comes to my Kubernetes persistent storage aspirations.

Micro SD cards are not the right choice for Kubernetes-based workloads. With random r/w will be all over the place, these cards, which were designed for digital cameras, is not the smart choice.

Even though this was a no-brainer, I wanted to educate myself further so I went through the following articles:

microSD Card Benchmarks (Raspberry Pi Dramble)

microSD Card Benchmarks and Reviews (Camera Memory Speed)

Another obvious reason was the shared storage element. I wanted storage that can be shared across the cluster while still fits the small dimensions of the setup.

There were 3 parts in order to achieve this – the actual storage drive, a Pi USB adapter and a cable which will be short but with high quality.

For the storage drive, I decided on the Samsung 860 EVO SATA III mSATA SSD drive (MZ-M6E250BW). 250GB is more than enough for my setup but the combination of size, performance & price for this drive was perfect.

In order to make this compatible with my setup (and any Raspberry Pi configuration for that manner), a Storage Expansion Board which is needed. For this, SupTronics Raspberry Pi 3 X850 V3.0 USB 3.0 mSATA SSD Storage Expansion Board was my choice.

You can read all the details and spec in the link below but I would highlight a few things:

  • USB 3.0 is very important here which this board supports. As a matter of fact, it supports USB 3.1 and it is 3.0 compatible.

  • You can go all the way to 1TB drive with this expansion

  • Bus powered, No additional AC adapter required

  • Ultra-compact size

  • Since I am using a USB cable to connect the board+the drive to the Pi, I am not using the small USB adapter you see on the right in the pics above.

The USB cable which comes with this board is long, ugly and not “tiny setup friendly” which is my I decided to look for something else. You will be amazed by how much time it took me to find a Male to Male USB 3.0 Cable on Amazon which will meet the right measurements.

As you can see in the pics below, the before and after speak for themselves.

Obstacles to overcome

The designed, original way of installing and connecting to storage expansion board to one of the Pi’s was not gonna work the way this setup was built.

The size, shape of the case, the way the Pi’s are connected to the case (with the acrylic plates) and the number of PI’s forced me to be creative.

I had to mix some of the screws for the case kit with what I had gotten from the storage expansion kit. I hope the below pics will help you understand.

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