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This document contains only my personal opinions and calls of judgement, and where any comment is made as to the quality of anybody's work, the comment is an opinion, in my judgement.
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A long time ago there was a computer called the
VAX 11/780
and it was the first popular 32-bit
mini-computer
and it defined a metric called
VUP
which very approximately meant 1MIPS CPU per 1MiB RAM, which is still
a ratio that is worth considering for balanced contemporary computer
systems. The main idea is that much larger RAM sizes require much
faster CPUs, in proportion, as the purpose of computation is to
process data in a given amount of time, and increasing very much the
amount of data processable without increasing processing speed is
likely to be not cost-effective.
There is an equivalent balanced ratio for storage which for me is 1TB capacity, 100 random IOPS, 100MB/s sequential transfer rate (of the storage device, but also of the network interfaces if serving to clients), which holds for many workloads. Increasing capacity should result in increased IOPS, so IOPS per TB remain constant, so workloads don't slow down when handling larger amounts of data, and also sequential transfer rate grows with capacity, so the time to fill or read a storage device does not grow a lot, which is important for maintenance operations like checking and backups.
