Rhodri Marsden: The cloud can burst, so best have a brolly handy

Cyberclinic

Millions of blameless internet users were put in the awful position last week of being forced to look at some other websites when the websites they were trying to access failed to load. Some of these people even had to resort to doing some work instead – a scenario they seemed ill-prepared for – and quickly took to whichever online forums they could access in order to vent their frustration. The cause? A screw-up by Amazon. For you and I they're just an online vendor of books and DVDs, but for many internet entrepreneurs they're the pre-eminent hosting provider, the gateway between their service and the public. When Amazon's infrastructure partly fails – as it did for three days – websites can simply disappear, and there's not a lot anyone can do about it except wait.

Sites affected included Reddit, Quora and Foursquare; not household names, perhaps, but big enough to kick off a debate about the reliability of "the cloud". The likes of Quora love Amazon, because they provide instantly scalable hosting. So if their service suddenly booms in popularity, they don't have to invest in a truckload of extra kit in order to cope; Amazon takes the strain and simply bills for some extra cash. Pay-as-you-go, if you like. But ultimately you get what you pay for. Netflix, an online film vendor and also an Amazon customer, wasn't affected by the outage because it could afford to have contingency plans in place – in this case an instant switch to another data centre in a location other than Virginia (where all Amazon's problems were centred.)

This could just be a humdrum tale of services failing to work properly. After all, we have power cuts and bad weather occasionally, and these things can deprive us of heat, light or postal deliveries. Stuff happens. But we're being persistently beckoned by the likes of Amazon, Apple and Google to "the cloud"; all three will soon launch cloud-based music services in the UK, where all your music can be stored in the ether as disembodied files. And, as last week proved, there will be times when it doesn't work; accessing "What's Going On" by Marvin Gaye will, sadly, depend on a multinational company pulling its finger out.

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People are fond of sticking the boot into Apple and Google, it's true. The latest furore surrounds how much they know about the physical movements of their customers. A new Mac application called iPhoneTracker accesses data lurking in the bowels of your iPhone to present you with a timelined map of everywhere you've travelled since as far back as last summer. Initially you think "wow!" as you match up the map with your diary, checking off your trip to Shropshire or your wait at Heathrow. Then you wonder why this information needs to be stored for so long; so far no one, including Apple, has come up with a decent answer. Caching our locations on a short-term basis can improve the performance of the location-based services we use on our phones, but I've no idea why the details of my trip to Whitstable a couple of months back need to be stored anywhere. Android phones do a similar, although less invasive thing, memorising the last 200 times you used a wi-fi point, along with its location.

Predictably, the "if you've got nothing to hide" brigade swung into action in the aftermath of these revelations – but we all have things to hide, albeit of varying degrees of significance. Your partner could use iPhoneTracker to have a curious peek at where you might have been last week when you claimed to be on a business trip. Equally, the police could confiscate your phone and use it to check your movements against the alibi you gave for that murder you committed. Both very easily done, no warrant required. So either behave yourself, or use a less cutting-edge phone. And if you want to ensure your location isn't stored anywhere, it's probably best not to communicate electronically at all. Just to be safe.