We recently had a partially failed disk in a RAID-1 configuration which did not perform a write operation as requested. Consequently, the mirrored disks had different contents, and the file which contained the block switched randomly between two copies, depending on which disk had been read. (In theory, it is possible to read always from both disks, but this is not what RAID-1 configurations normally do.) Anyway, how would be the chances for PostgreSQL to detect such a corruption on a heap or index data file? It's typically hard to detect this at the application level, so I don't expect wonders. I'm just curious if using PostgreSQL would have helped to catch this sooner.
