If Pi Clusters were actually cost competitive for performance there would be data centres full of them.
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One day my primary Raspberry Pi broke (turned out to be a PSU issue), and I thought of having an old laptop running 24/7 as a home server. While being not very power hungry, it’s still wants much more energy (plus it has fans). For a casual usage (I forgot to mention Pi-Hole) it feels like an overkill. So, while a Raspberry Pi isn’t the best, it has its niche, and I’m happy of having one (actually, a few).