Computing notes 2022 part two

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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2022 July

20220710 Sun: Standard ratio for storage

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.

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