This paper has provided details on the LE of the data on magnetic tape, hard-disc drives, flash memory, and optical discs. For archival purposes, only the M-DISC presently meets the requirement of long-term data retention (more than 100 years). This disc has been rigorously tested, and the results are very positive.The main weakness of the M-DISC is its relatively small capacity. This weakness is being addressed by our current research on a permanent solid-state solution, one whose density will enable a capacity of several terabytes in the format of a solid-state drive. Though it will be much more expensive than an M-DISC, the convenience of having several terabytes in a single, removable form of storage should be very attractive to the archival community.