The disappearing notion of storage

In the beginning was the processor. And it was good. But the processor needed data to act upon, and lo! there was memory (in the form of mercury delay lines). But the processor and the memory worked only while powered, and we needed a way to store the data in the long term (that is, when the machine was not powered) and so there came storage devices.

Storage devices evolved along a tortuous path. From punch cards to magnetic tape, from paper tape to DECtapes (which were not quite the same as plain magtapes), and then to magnetic platters that were eventually called "discs".

The path for microcomputers was slightly different. Microcomputers started with nothing, had a short stint with paper tape and cassette tape, took off with floppy disks, then hard disks, and finally (eons later) flash thumb drives and solid-state disks (SSDs).

A computer needs storage because everything that we want to store is bigger than memory. The company's accounts would not fit in the 4K of memory (especially with the general ledger program and tape libraries sitting in memory too) so the data had to live somewhere. Removable media (paper tape, magtape, disks) made for an auxiliary memory of virtually infinite capacity.

But what happens when a computer's main memory becomes large enough to hold everything?

I've made the argument (in another forum) that virtual memory is sensible only when the CPU's addressable memory space is larger than physical memory. If the processor can address 16MB of memory (including all virtual pages) and the computer contains 4MB of memory, then virtual memory works. You can allocate memory up to the 4MB limit, and then swap out memory and effectively use 16MB of memory. But give that processor 16MB of memory, and there is no need for virtual memory -- in fact it is not possible to use virtual memory, since you can never have a page fault. (I'm ignoring the CPU designs that reserve address bits for virtual memory. Assume that every address bit can be used to address real memory.)

Computer memory has been limited in size due to a number of factors, one being manufacturing capabilities and costs. It wasn't possible (read 'feasible with the budget') to obtain more than a paltry few kilobytes of memory. External storage was slow but cheap.

The cost factor has just about disappeared. With solid-state disks, we now have lots and lots if bits. They happen to be organized into an entity that pretends to be a storage device, but let's think about this. Why pretend to be a storage device when the CPU can address memory directly?

Here's what I see happening: CPUs will change over time, and will be equipped with larger and larger addressing capabilities. This will require a change to physical architecture and instruction sets, so I expect the change will occur over decades. But in the end, I expect a computer to consist of a CPU, memory, video, and a network port. No USB ports. No memory sticks. No serial port. No keyboard port. And no hard disk drive. You will load applications and data onto your computer. They will be stored in memory. No muss, no fuss!

Such changes will mean changes for programs. We won't need the elaborate caching schemes. We won't need "save file" dialogs. We won't need disk de-blocking routines or special drivers for spinning metal platters.

Not everything changes. We will still need backup copies of data. We will still need transactions, to ensure that a complete set of changes is applied. We will still need names for data sets (we call them 'file names' today) and we will still need to grant permission to use selected parts of our data store.

So I wouldn't toss the concept of file systems just yet. But be prepared for changes in hardware to rock the boat.