On both days, large amounts of traffic caused by the Mother’s Day weekend meant that the UK web servers were unable to respond in a timely manner to requests. This resulted in UK based diaries running slowly and/or becoming unresponsive. An on-call emergency support engineer was alerted promptly on the 10th and attempted a low-risk procedure on the UK servers to alleviate some of the stress they were under. This procedure helped the situation but did not completely resolve the issue. At this time, the servers were becoming responsive again, so the decision was taken that it was not in the best interests of our customers to perform higher risk fixes in the middle of service on Mother’s day weekend.
On the 11th, a similar incident occurred at around lunchtime and our emergency support engineers, having anticipated the recurrence, performed a procedure that routed a portion of the traffic to other servers, thereby greatly reducing the stress on the original web servers. This resulted in an immediate drop in load on the servers and UK diaries became responsive again.