Google's lost emails were apparently restored from Oracle StreamLine 8500 tape libraries using LTO drives.
Up until now the tape infrastructure Google used to restore its lost emails has been unknown. Our understanding from informed industry sources is that Google has 16 StorageTek StreamLine 8500 tape libraries with both StorageTek proprietary tape drives and IBM LTO drives.
The lost Google emails were retrieved from LTO format tapes via the IBM drives.
This is one of the greatest tape library customer reference stories ever and it's not public. Amazing. ®