It seems to be the year for disk failures.
The good news is that the RAID array has done its job, no data loss so far, I’ve got completely up to date backups (which I know restore properly), and engineers are looking at the physical server right now.
As a precaution, new reviews, new comments, and the members area have been disabled till the problem has been fully resolved. Don’t want to risk losing anyone’s new contributions if things go horribly wrong. It’s also probable that the server will be offline for a period while hardware is replaced. Fingers crossed the faulty kit will be replaced soon, and we’ll be back to business as usual.