Although Googles backup service was initially unsuccessful in its efforts to save the data, the company said only 0.1 per cent of disk space had been affected, and has since been reduced to 0.000001 per cent.
The lightning strikes occurred last Thursday, and since then Google has been able to restore most of the data that was initially lost.
Four strikes hit the electricity grid that powers facilities in Saint-Ghislain, affecting 5 per cent of non-virtual disks in the zone that powers Google Compute Engine, its cloud computing platform.
Google commented on the events by saying: ”In almost all cases the data was successfully committed to stable storage, although manual intervention was required in order to restore the systems to their normal serving state.
“However, in a very few cases, recent writes were unrecoverable, leading to permanent data loss on the Persistent Disk. This outage is wholly Google’s responsibility.”
Google has since said it is upgrading its storage hardware, making it less vulnerable to failure.