powered occasionally to hold data

A bit more detail: simply being powered on won't necessarily stop that.

You want something checksumming the data and making sure it's not silently rotting off the disk.

ZFS does this, something like snapraid can do it too, and there's various other methods of making checksums you can validate data integrity with and be able to repair minor corruption. (PAR files, for example.)

A real-world example of this kind of oops is everyone's favorite Youtube Tech Personality(TM) LTT who lost a fuck-ton of data due to not scrubbing data on a ZFS array and had to go through months of restoration to get most of it back, so uh, yeah, make sure you've taken steps to detect and correct the bitrot that's going to happen anyways.