One thing I’ve been doing lately is storing data on SSDs or raid0s of SSDs, then running continuous backups of changed files to a slow HDD. I don’t have single-transaction data safety requirements and the window in which I can lose data is very small, given that the backups run continuously.

This is so much faster than these hyper-vigilant HA setups, too, while being quite a bit cheaper (the HDDs can be in a different box or building, or be Glacier, or whatever).