There is a storage related flag --storage-items-per-batch. According to the documentation this flag is used to set "The number of edges and vertices stored in a batch in a snapshot file.". The deaful value is 1000000. What does this mean? That I can retrieve only last 1000000 edges and vertices stored in a last batch? Can i have a data loss when restoring db from snapshot?
This option (storage-items-per-batch) is used during snapshot creation, not during the restore operation. It controls the internal layout of the snapshot file on disk, in an attempt to efficiently use whatever CPU cores are available on your hardware. The only risk is related to throughput. There is no risk of data loss.