Internet giant Google blamed Monday's Gmail woes on a storage software update but said that the deleted email had been restored from tape backups.
The company said that 0.02 per cent of Gmail accounts were affected by the web mail glitch that saw users open their account to find all previous email gone. The revised figure equates to roughly 40,000 accounts out of 200 million Gmail users.
Google 'reliability czar' Ben Treynor answered the self-posed as to how the firm could lose email stored across multiple servers in multiple data centers, saying: "Well, in some rare instances software bugs can affect several copies of the data."
Just such a bug found its way into an update of the firm's storage software system. When issues became apparent Google stopped the software roll out.
"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," Treynor said.
The last status update says that the missing email has been restored from tape but it would take a little longer to move the data into the remaining affected Gmail user accounts.