Fail-safe protects historical data in case there is a system failure or any other failure.
Fail-safe allows 7 days in which your historical data can be recovered by Snowflake and it begins after the Time Travel retention period ends.
It is important to note that Fail-safe should only be used when all other recovery options have been tried and it can be used only by Snowflake in order to recover data that may have been lost due to any types of system failures.
Lastly, recovering data through Fail-safe can take hours to days.