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.