While some of those files were lost temporarily, others are permanently gone. According to Google, 5% of space on the persistent disks experienced failure in the August 13th incident. Approximately 0.000001% of disk space was permanently affected.
Even though there are multiple levels of power surge protection measures at data centers, recently saved files were also affected by the electrical strike.
“The issue only affected Standard Persistent Disks that existed when the incident began at 09:19 PDT. There was no effect on Standard Persistent Disks created after 09:19,” explains Google’s online report.
The company has taken full responsibility and apologized for the incident online.
While it’s incredibly unlikely for four lightning strikes to hit the exact same spot, it only needs to strike the broader infrastructure to cause a compounded problem.
“The cabling alone can be struck anything up to a kilometer away, bring [the shock] back to the data center and fuse everything that's in it,” Justin Gale, project manager for the lightning protection service Orion, told the BBC.
While power was swiftly restored by automatic auxiliary systems, data loss still occurred.
“Everything in the data center is connected one way or another,” noted James Wilman, engineering sales director with Future-Tech. “If you get four large strikes it wouldn't surprise me that it has affected the facility.”