Facebook: Photos Lost Due To Hard Drive Failures
However, Facebook said, the deletion is temporary, and that all the photos should be available again shortly.
Facebook said in October that its users had uploaded more than 10 billion photos.
Evan Priestly, an engineer at Facebook, wrote late Sunday in a blog posted on Facebook that several users reported problems with photos being replaced by question marks on the site.
Priestly wrote that the problem affected between 10 percent and 15 percent of photos that were previously uploaded to Facebook.
However, Priestly wrote, those photos are safe and are being reloaded.
The problem arose when Facebook on Friday night did a routine software upgrade and a number of hard drives on which the photos were stored apparently failed at the same time. "We're trying to fully understand what happened, since simultaneous hardware failures like this are rare," he wrote.
The photos are safe, Priestly wrote, because multiple copies are stored just in case of unusual hardware failures such as the one experienced this weekend. However, he wrote, the missing photos have to be restored to the affected storage volumes after they are repaired. "We're working on them right now, but it will take some time because there's so much data on them, and the repair process largely involves copying huge amounts of data to new drives," he wrote.
Facebook had expected to repair about two-thirds of the affected photos by late Sunday night and have everything available by early this week, Priestly wrote. During the repairs, however, new photos can be uploaded. "We write them to different storage volumes," he wrote.