Walking around professional trade shows can yield some interesting encounters: the MnemosBOX is a Rackable Blu-Ray jukebox that can read/write 16TB of data across 200 standard Blu-Ray optical discs. It gets even better as it is possible to link 8 units to scale the available storage linearly.
This storage system is designed for “cold storage” of data, which means that it is cost-efficient (per GB) for data that is rarely accessed such as archived. It could be used instead of, or in addition of tape storage, since tapes and optical discs have different properties and resilience. Optical discs are not sensitive to magnetism for example.
Since optical discs aren’t as fast as hard drives or SSDs, it is possible to use a classic HDD/SSD as a cache system to boost the performance for commonly accessed data, if needed. This unit is a network storage system that uses CIFS / NFS with a network share.
When I looked at the administration interface, the discs showed up as individual volumes. There’s also an option to share the storage capacity as a single virtual volume, which would be more intuitive to use or manage.