Thanks for the response. fsync and full_page_writes are both on.
Our database runs on a managed hosting provider's vmhost server/san, I can possibly request for them to provide some hardware test results - do you have any specifics diagnostics in mind? The crash was apparently due to our vmhost suddenly losing power, the only row that it has complained with the chunk error also migrated into both standby servers, and as previously stated was fixed with a reindex of the parent table in one of the standby servers after taking it out of recovery. The vacuumdb -avz on this test copy didnt have any errors or warnings, im going to also run a pg_dumpall on this host to see if any other rows are problematic.
Is there something else I can run to confirm we are more or less ok at the database level after the pg_dumpall or is there no way to be sure and a fresh initdb is required.
I am planning on running the reindex in actual production tonight during our maintenance window, but was hoping if that worked we would be out of the woods.