How do you know you put good data into the cache in the first place?
There's always going to be a place where errors can creep in. There are no absolute guarantees; it's a numbers game. We've got more and more data, so the chance of corruption increases even if the per-bit probability stays the same. Checksumming reduces the per-bit probability across a whole layer of the stack - the layer where the data lives longest. That's the win.
I was asking this thinking of open(<file>,O_DIRECT|O_RDONLY);
that bypasses buffer cache and read directly from the disk that atleast solves buffer cache i guess. The disk cache is another thing ie if we disable it we are good at the cost of performance.
I was pointing that tests can do these kind of things.
There's always going to be a place where errors can creep in. There are no absolute guarantees; it's a numbers game. We've got more and more data, so the chance of corruption increases even if the per-bit probability stays the same. Checksumming reduces the per-bit probability across a whole layer of the stack - the layer where the data lives longest. That's the win.