iOS 5 update for iPhone and iPad puts huge strain on Apple's new iCloud servers, leading to slowdowns for many users

Demand for Apple's update to its iPhone and Mac software to enable its "iCloud" services caused a gigantic surge in internet traffic in Europe.

Throughput in the UK jumped by 200 gigabits per second – equivalent to more than a fifth of normal traffic – a spike that lasted for roughly four hours.

The colossal demand, which was mirrored around the world as the update became available from the company's servers at 1800 BST on Wednesday, will have been the severest strain on the cloud systems that Steve Jobs showed off in his last major speech in June.

The normal daily ebb and flow of internet traffic through the London internet Access Point suddenly changed when the iOS5 update was released at 6pm BST on Wednesday

The demand led to slowdowns for many trying to download the software, and then to errors as their systems tried to connect back to Apple's servers, which had to verify the update on each device.

Many feared that the update had "bricked" their phone and rendered it useless – but then found that it worked once Apple's servers came back online.

Data from the London Internet Exchange doesn't seem like a dramatic growth - but the uptick equates to 200 gigabits per second

Jay Freeman, an iPhone expert, tweeted an explanation: "To anyone getting 'An internal error occurred' (3200) while installing iOS 5.0, Apple's servers are swamped, and failing half the requests."

The download was the sternest test that Apple's servers will have endured so far as millions of owners of iPhones and iPads able to run the new software tried to access it.

However, the shift to iOS5 and iCloud should mean that Apple will in future avoid such gigantic rushes in demand. Future versions of the software can be downloaded "over the air", so that it will be able to pace the rollout of new versions of the software to iPhones, iPads and iPod Touches on a country-by-country or other basis, in order to ease the load.

Germany's Berlin Internet Exchange also saw a huge spike in traffic

The iOS5 update brings a number of changes to the software, many of which make it more directly competitive with Google's Android: it introduces a system-wide "notifications" system as well as the over-the-air updating, both of which already feature in Android.

However, iOS5 does not bring – as some upgraders seem to have expected – the "Siri" voice recognition assistant: though it was previously available as a free app for the iPhone 3GS upwards, it is now only available on the iPhone 4S, which goes on sale on Friday.

The monthly view of the traffic through the Berlin internet exchange

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