If you need fast and regular access to the archive, anything up to 1 PB can be handled with HDDs nowadays. If you dont need that, LTO tape will be much cheaper. For your offsite backup encryption+archival storage such as GCP coldline or archival storage is very cost effective and can be combined with either. Think about your data and organization. Perhaps you only need fast access to a part of the data, so combining the two might be the best solution. Consider if you have an IT department or a data steward to set up a system for organizing that data.