04 June 2018

A Hop, A Skip, and A Jump - part the fourth

During my near awake status, it occurred to me that the I5 System (nee, AS/400) would be the perfect candidate for PM. The machine after all, doesn't use a file system in the *nix/Windows sense, but an object store (in the pure data sense). It's machine designed, however well applications exploit it, to be Relational.

Turns out, some folks already have. And not just with the Optane announcement.
But key here is that when the object gets created, it is also created in a system-wide address space that IBM i calls Single Level Store (SLS). In the context of this article on persistent storage, it happens that SLS is also persistent; if you restart the OS — say after a power failure — the objects remain with the same address. Said differently, every byte of data out on your hard or solid-state drive has a corresponding location-independent high-level address used by the OS. If your program wants to reference that byte in whatever object, your program just uses the byte's address, no matter how many times the OS was restarted.

Some folks consider IBM to be a hidebound dinosaur. And, to some extent that's right. But here's a bit of history of the I5 OS:
IBM's design of the single-level storage was originally conceived and pioneered by Frank Soltis in the late 1970s as a way to build a transitional implementation to computers with 100% solid state memory. The thinking at the time was that disk drives would become obsolete, and would be replaced entirely with some form of solid state memory. IBM i was designed to be independent of the form of hardware memory used for secondary storage. This has not come to be, however, because while solid state memory has become exponentially cheaper, disk drives have also become similarly cheaper; thus, the price ratio in favour of disk drives continues: very much higher capacities than solid state memory, very much slower to access, and much less expensive.
[my bold]

A few years ahead of his time.

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