Yesterday, TalkinCloud told you about a Google Gmail glitch that affected as many as 150,000 users, wiping out their data and bringing them back to Inbox Zero — the hard way. Well, in an official blog entry, Google apologizes while reassuring the .02% (wasn’t it .08% yesterday?) of Gmail users that they’re working hard at recovery, and the missing data has been found — on old-school tape drive backups.

Doesn’t Google maintain multiple copies of all messages and documents across their many data centers? That blog entry says the answer is “yes,” but a problem with a  storage software upgrade caused data to vanish into thin air. Google pulled the plug when the company realized what was going on, which is why the glitch affected less than a percent of users rather than millions.

So Google’s tape backups, being unaffected by the software glitch, remained intact. But that’s why it’s taking hours and days for engineers to restore the data. And any messages sent to an affected user between 6:00 p.m. PST on February 27 and 2:00 p.m. PST on February 28 almost certainly never made it.

So why is this notable for cloud services providers? It may require a thinking of the cloud storage approach. Companies like BUMI and Storage Guardian pitch their cloud backup and recovery products as being a 21st-century approach to filling the same niche as tape backup.

But when Gmail’s cloud fails at recovery and Google’s engineers need to turn to tape backup, well, it raises questions. Especially with a company as influential on the subject of public cloud services as Google.

Follow Talkin’ Cloud via RSS, Facebook and Twitter. Sign up for Talkin’ Cloud’s Weekly Newsletter, Webcasts and Resource Center. Read our editorial disclosures here.