SSDs can fail in weird ways. Some spew garbage as they're failing,
some go read-only. I've seen both. I don't have stats on how common it
is for an SSD to go read-only as it fails, but once it happens you
cannot fsck it. It won't accept writes. If it won't mount, your only
chance to recover data is some kind of offline scrape tool. And Btrfs
does have a very very good scrape tool, in terms of its success rate -
UX is scary. But that can and will improve.
--
Chris Murphy