A few more reasons against I haven’t seen yet.
Single company of failure. I could replace a Dell x86 with an HP fairly painlessly. I could not replace a rpi with a beaglebone black or other arm as easily, especially if I was using non-USB peripherals. It’s not as easy as “plug in install disk and go.” You need a plan for when they stop making or supporting your part. Embedded systems are not standardized like pc-compatibles.
No integrated server management. I mentioned it in a comment, but the lack of IPMI or similar is a pain; someone must physically be there to service it whether it is the middle of the night or on Christmas morning.
No hardware/OS support available. Have a problem running a COTS application? Driver issue causing crashing? You’re probably on your own. Replace computer and/or application.
ARM architecture. If it’s not FOSS, it probably won’t run here. No driver blobs for many printers either.
SD/microSD-based storage. Try compiling something. Anything. Bring a book. This is a pretty big problem for any RDBMS with even low/moderate activity.
And now for something completely different.
Here are a few reasons you should use a raspberry pi as a server.
You have non-traditional requirements
- You need a server that only runs on batteries.
- You need a disposable server that you won’t mind getting broken or lost.
- You need a (cheap) server that is vibration tolerant.
- You need a lightweight server.
- You need a volumetrically small server.
Potential applications.
- Your server must fly. By itself. You’ve got it mounted on an aerostat, a high altitude balloon, or a UAS. It coordinates with your Swarm-Drone OS and provides a convenient cli for multi-user remote control. All under 400′ unless granted FAA clearance, of course.
- Your server is actually an urban art project on the omnipresence of technology in modern life. It’s ziplocked and taped to the apex of the clocktower where it will remain until someone goes up to scrape it off. It’s about time the old tower was ntp-enabled anyway.
- Your team takes words like “agile” and “velocity” way too literally. Your idea of a scrum is the 15 seconds it takes to make an 8-way skydiving formation and you only to commit to mercurial while moving >90mph. It’s just easier if the server is moving at the same speed.
- Your company is actually a band of nomads in the northern sahara providing IT solutions to other nomads. Everything must be solar-powered and pack on a camel.