6月初，Visa欧洲区发生了技术故障，导致Visa交易被拒绝，故障持续超过10个小时。

现在Visa终于出来说原因了：

https://www.computing.co.uk/ctg/news/3034526/visa-rare-networking-switch-failure-to-blame-for-payments-glitch-earlier-this-month

澄清信：

https://www.parliament.uk/documents/commons-committees/treasury/Correspondence/2017-19/visa-response-150618.pdf

摘录如下：

“Specifically relevant to this incident, each data centre includes two core switches (a piece of
hardware that directs transactions for processing) – a primary switch and a secondary switch. If
the primary switch fails, in normal operation the backup switch would take over.

In this instance, a component within a switch in our primary data centre suffered a very rare partial
failure which prevented the backup switch from activating. As a result, it took far longer than it
normally would to isolate the system at the primary data centre; in the interim, the malfunctioning
system at the primary data centre continued to try to synchronise messages with the secondary
site. This created a backlog of messages at the secondary data centre, which, in turn, slowed down
that site’s ability to process incoming transactions. ”

简单来说就是主从备份的switch发生一个罕见的故障导致从备份无法激活。

世界杯前，MasterCard是公关事故，Visa是技术故障，看来都好不到哪去。