Thanks for making this point. If you access your memory sequentially, as Varnish does, great. But if you need to stride across a giant matrix in transposed orde

Thanks for making this point. If you access your memory sequentially, as Varnish does, great. But if you need to stride across a giant matrix in transposed order, you'll bring your spinning disk backed virtual memory to a halt, as it does a million seeks. To use virtual memory successfully you have to write in-memory algorithms that recognize the non-random-access nature of the memory. If you had simply acknowledged there's a storage system, you wouldn't put out much more effort, if any, to get the same performance. In fact, by pretending it's all RAM, you give up the opportunity to overlap your I/O and do something useful with the time the system would have to spend paging in your data. Edit: btw, happy and satisfied Varnish user for many years!