Microsoft has serious questions to answer after perhaps the biggest IT outage in history

It's possible we are looking at the largest IT outage in history.

More than 70% of the world's desktop computers run on Microsoft Windows software.

A software update from one of Microsoft's clients - cybersecurity company CrowdStrike - has now taken a large number of those machines offline.

The faulty code - just a few lines long - has led to global disruption with an economic impact that is as yet incalculable - but likely to be huge.

The "Falcon Sensor" product designed to protect Windows from malicious attacks is used widely on Mac and Linux systems as well as within more bespoke software for things like cash machines.

Thankfully, the update that caused the Microsoft meltdown did not affect these other software families - if it had, the impacts could have been catastrophic.

Serious questions

There are serious questions of course for CrowdStrike.

But there also serious questions for Microsoft. What due diligence do they perform on third-party providers and on individual updates before they are released across their globally dominant system?

There are questions too for anyone whose livelihood depends on IT products made by an increasingly powerful oligopoly of tech companies.

Any engineer will tell you over-reliance on one system leaves you open to a "single point of failure". Critical digital infrastructure has to have redundancy - back up systems - built in to ensure it is resilient.

Thankfully, it seems IT in emergency services, hospitals, air traffic control, water and power utilities and government departments have come through largely unscathed.

That is reassuring.

But for everyone else, the global disruption caused by a bit of routine IT maintenance raises profound questions about the reliability of the software on which the world runs.