All my spinning drives are RAID1. When either one fails, I replace it.
There's also a nightly backup. I suspect the price of SSDs may have
reached the point that when I lose my next spinning drive, it'll be time
to get serious about transitioning to them.
Note, so far as I'm concerned, all disks should be RAID1, even if
there's only one drive in the array. When the time comes to upgrade
capacity, there is no easier way to do it than add the new drive to the
array, wait for it to sync, remove the old drive, and resize the