A problem with one of Tumblr's database clusters took the site down sometime between 7 p.m. and 8 p.m. Eastern time. The site announced the outage on Twitter, saying it was "incredibly sorry for the inconvenience."
Early Monday morning, Tumblr was still struggling to correct the problem. "This has been a slow painful recovery, but we're almost through," the site tweeted. "We'll have more info to share as soon as we can post to our blog again."
Tumblr did not say when that might happen. Impatient users took to Twitter to vent in English, Spanish, Japanese and other languages. "Tumblr not working is ruining my life. How much longer will this madness last!! I need my Tumblr," Melodie Davis tweeted.
Others with apparently less at stake were flippant: "Has anyone tried turning it off and back on again?" Diana Parkhouse said.
Twitter as sounding board for Tumblr users comes as the former has lost a couple of celebrities who've chosen to blog rather than tweet. The biggest public relations coup occurred in September, when singer/songwriter John Mayer dropped Twitter in favor of Tumblr. Writer and comedian Ricky Gervais cancelled his account early this year, preferring to do his social networking through his blog. This doesn't mean Twitter use is falling. In June, the company hit a record 2 billion tweets per month, which translates into 64 million tweets per day, according to Pingdom.
Tumblr has also been growing. Each day, Tumblr's 7.5 million users make 5.3 million-plus posts, according to the site. About 50% of the posts are photos, with the remaining half split among text, links, quotes, music and video.
Tumblr is best known for its tools that make blogging very easy. Competitors include TypePad, WordPress and Posterous.