Twitter's downtime last weekend was not unusual, according to Pingdom, which has been tracking Twitter's performance since mid-February. Right now they're at about 98 percent availability, which sounds good but actually adds up to quite a few hours of downtime each month. Here's Pingdom's summary:
We have monitored the availability of the Twitter.com website since mid February 2007 until today (and counting). So far, the accumulated downtime of the website totals 5 days and 23 hours. This includes maintenance, but is still a very high number. So far in December, the website has been unavailable for a total of almost 11 hours (part of which was due to problems related to a data center move).
As we noted earlier in the week, there hasn't been a user revolt as yet. For most folks, Twittering clearly isn't rise to the level of a mission-critical application. But with the emergence of services ranking the most powerful Tweeters, there may yet emerge an ecosystem and business model that will demand better uptime. Pingdom has added a Twitter tracking page to monitor the service's uptime.