Last month we had an article on whether tape backup was obsolete, which discussed some of the reasons why many organizations continue to use tapes. One of the outfits is Google, and this week those tape backups proved invaluable to a group of Gmail users whose email boxes disappeared during a software update. When a bug wiped out Gmail boxes, Google turned to the tape to restore the data.
"I know what some of you are thinking: how could this happen if we have multiple copies of your data, in multiple data centers?" wrote Ben Treynor, VP Engineering and Site Reliability Czar. "Well, in some rare instances software bugs can affect several copies of the data. That’s what happened here. Some copies of mail were deleted, and we’ve been hard at work over the last 30 hours getting it back for the people affected by this issue.
"To protect your information from these unusual bugs, we also back it up to tape. Since the tapes are offline, they’re protected from such software bugs. But restoring data from them also takes longer than transferring your requests to another data center, which is why it’s taken us hours to get the email back instead of milliseconds."
Google says it will release a full incident report once its analysis is completed. The company said the bug affected 0.02 percent of Gmail users.