TypePad, a developer of self-publishing software for Weblogs, said its service has been down since Thursday night due to a problem with its primary storage system.
In a statement posted on the Web site of TypePad owner Six Apart Ltd., the company said it "experienced an issue with our primary disk system where data from published blogs are stored."
"We are currently running diagnostics on the device, and working to restore your data as soon as possible," the statement said.
"Verifying data can be a slow process and will take time."
TypePad said it was deploying backup copies of customer blogs from approximately two days ago.
That data will be displayed on blog sites.
However, users will be unable to log into the site because the TypePad application is unavailable.