I am thinking of running multiple database/messages servers such as postgres, redis, mongo, influxdb on old computers and use a centralized NAS to store the data.

One advantage is that I don't need to worry about getting appropriate local storage for the computers that host these services. For example, I could run postgres on an old desktop with spinning disks or even a raspberry pi.

But I am still concerned about the I/O speed and reliability. I wonder if anyone has experience doing it like this. Can you share the pros and cons? I really appreciate it.