The original post where
bob432626 wrote: ↑
Sun Oct 13, 2019 6:28 am
pretty much all the pis worked together as 1 computer
makes me think the question is not about traditional RAID with a single Pi but how to set up a fail-safe distributed filesystem using multiple Pi computers.
It is widely documented how to configure a single server with a redundant array of disks. In my opinion RAID works well up to about 100TB. For petabyte storage requirements, however, a distributed approach may be preferable for greater resiliency as well as bandwidth.
Ceph generally requires separate computers for the monitor, manager, metadata server and the online storage devices. A realistic setup might consist of three monitors, two managers, two metadata servers and three or more online storage devices. That's already at least 10 computers, which is quite a few just to set up an environment for learning about things at home.
Luckily, many people have the budget to buy and provide the electricity for that many Raspberry Pi computers--even the 4GB model. This allows someone, who wouldn't have had an opportunity otherwise, to become an expert in setting up and maintaining high-performance distributed filesystems.
At the same time, it might be more productive to set a Pi-controlled drip sprinkler system up for growing tomatoes in the garden.