The servers that run our clients’ websites and email live in a data centre rather than an office cupboard, which means redundant power, proper cooling, and a network connection that doesn’t depend on one cable.
This week a second fiber line went live into our rack.
The reason isn’t speed, although that helps. It’s that a single connection is a single point of failure. Fiber gets cut. Equipment fails. Providers have bad days. One line means a bad day for them is a bad day for every site and every mailbox we host. Two lines from that point on means an outage has to happen twice before anyone notices.
When it went live we measured it properly rather than trusting the paperwork, and that’s worth a word.
A single download test is a bad measurement. One connection to a server a long way away is limited by the distance as much as the line, so it under-reports badly — our first test showed a fraction of the real figure and looked alarming. Running several transfers at once against a server nearby gave the honest number, and the line delivers what it should.
We also checked the network card’s error counters before and after, because a connection that looks fine while quietly corrupting packets is a problem that only shows up as things being slow for no reason.
None of this is visible to anyone whose site we host, which is the point. Infrastructure work is successful when nobody has a story about it.