Backups
The biggest threat to digital libraries is losing the information stored on computers. Regular backups are taken and stored in safe and secured places. These backups can run into Gigabytes and Terabytes. The most suitable storage device for these backups is external hard disk. These are easy to transport and to store. Smaller libraries can take backups on DVDs (upto 8.5 GB/disc) and Blue ray discs. A single-layer blue ray disc can hold 25GB. A dual-layer blue ray disc can hold 50GB.