For a long time, I have pictured Raspberry Pi as the perfect computer. It’s cheap, its price is low, the manufacturing costs are minimal.

To me, the most significant advantage of a Pi to a conventional computer is:

“I won’t feel any remorse after accidentally breaking a Raspberry Pi or ripping it apart.”

So why aren’t Raspberry Pis used everywhere? Turns out Pis are known to the State of California to cause [REDACTED], if consumed.

All jokes aside, there are projects that Raspberry Pi simply cannot handle. Here are some examples.

Servers/Clusters

Raspberry Pi as servers is a horrible idea. Slow and unreliable I/O, weird software support, slow non-ECC RAM are only parts of the issue.

Practicality

Mantaining a rack of hundreds of Pis is already a nightmare. Just imagine going through hundreds of ethernet cables to reach your Pi. What about auto-updates?

Resource Efficiency

Scaling the infrastructure is also hard, and at best, each Pi will have plenty of wasted CPU and RAM resources.

Why would there be wasted resources? Imagine this scenario:

You have 16 Raspberry Pis, each with 4GB RAM and 4 CPU cores.

You have 16 tasks, each taking 3GB RAM and 3 cores.

You have to use all of the 16 Pis.

Congratulations! You wasted 25% of all available computing powers.

Now consider the alternative:

You have 1 mainframe with 48GB RAM and 48 cores identical to the Pi’s core.

You have 16 tasks, each taking 3GB RAM and 3 cores.

You used all your available computing powers.

No computing power is wasted.

Power Efficiency

What really trips the hook is Pi’s power efficiency. According to this article, an idling Pi 4 consumes 4W of power.

In comparison, in my previous post, an idling Intel mobile 4-core CPU consumes 0.5W.

Even worse, for large Pi clusters that adds up.

Please, for your own sanity, DON’T build a large Raspberry Pi cluster. Aside from being a fun project, its inefficiency is to the extreme. Managing such cluster is also a pain (Based on real-life experiences).

IoT with limited power

4W of idle power consumption simply is too high. Other IoT solutions such as ESP-32 are designed for this.

As a bonus point, ESP-32 and similar solutions handle varying battery voltages nicely.

Anything that requires reliability

Raspberry Pi is really not designed to be reliable. I had constant USB drive issues with it. Sometimes, my Pi resets randomly. Another time, it completely trashed my microSD card.

Router

It only has one ethernet port! and USB ethernet adapter is not an option due to Pi 4’s reliability issues with USB ports.

On the contrary, the Compute Module 4 makes a perfect router, if you can attach the PCIe lane exclusively to an ethernet PHY. Of course you can.

Do not use Raspberry Pi’s wireless adapter as the wireless transmitter for your router. Instead, buy a proper wireless router or at least a good wireless adapter.

Cryptocurrency miner

It is not feasible. I did the calculations myself.

Emergency food

WARNING: This product can expose you to chemicals including Lead and Polychlorinated biphenyl, which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

I thought that was funny.

When to Pi?

If you want to build a Raspberry Pi cluster, please kindly listen to this piece of advice: DON’T. Unless you are doing it for fun, of course. Otherwise, please rent a server in a datacenter.

If you want to build a small project that involves some minor computations and interacting with the physical world, Raspberry Pi is perfect.