The Japanese FujiFilm has been developing new magnetic materials for tape with an eye towards higher capacity designs. The latest material is Barium Ferrite, but work with Strontium Ferrite has shown even finer grain structures.
The scale of the material is large by semiconductor standards but the improvement with Strontium Ferrite is obvious. Hard disk plates are typically aluminum with the magnetic material applied by sputtering. Glass media are seen in some laptop disks. Tape is still far behind hard disks in terms of the density of data per square inch.
The smaller grain material can being in larger capacity tape assuming that the stuff remains firmly in place on the tape. SrFe particles are down around 5nm in size which is boulder by semiconductor standards, Still a tape drive can leverage this and possibly reach 1PB on a tape. PB tapes would be desirable in the archival business as hard disks have struggled to increase capacity.
Stuffing a 1PB tape drive in a gamers rig would handle every game hoard easily. The tape would saturate M.2 SSD speeds given the speed that LTO media move at. Still 1PB would allow games galore to be saved when not in use. The linear tape file system make tape as easy to use as a hard disk.
Right now data center hard disks are available and they top out at 18TB. 20TB disks are being tested in some corporate servers and if they survive testing then they may be mass produced for widespread use.
Over the next 5 years tape may well get ahead of hard disks. If that happens then storage tiers will change with various cloud services. 1PB tape may be 7-8 years down the road but if that surfaces there could be some real change in archive vs active storage tiers.
Today LTO-8 tape handles 12TB native storage while LTO-9 offers 18TB. Upcoming tape formats will double capacity every few years. LTO-9 needs 400 MB/s bandwidth so either SSD or an array of disks are needed to handle the tape at full speed. Tape robots can easily migrate from older tapes to new sizes by simply copying the tape. The old tapes can be wiped and recycled securely.
Robots like the i6000 hold vast numbers of tape which ramp up with new capacity bumps every few years. While a tad expensive there are lots of customers for giant tape systems. NASA comes to mind as a big user but many other government agencies also use large archives.
The hyperscalers systems make the i6000 look like an entry level product. Some larger installations are enormous and hold millions of tapes. The reason large archives exist is due to astronomy which is archived pending some research project that may need some particular material. Retrieval time may be slow but even hyperscale systems are accessible.
High speed fiber internet makes large hyperscale systems viable. Users can access the data from anywhere.When 1PB tapes come to market giant archives will slowly migrate to new tapes but the process is migrating 1 million tapes is sluggish.
Facebook has to use RAM based servers to keep up with the 2.5 billion users. SSD servers are now becoming faster to take some pressure off the expense of vast arrays of RAM. Facebook is a good case study for overloaded web servers. Now Facebook has more money to afford a hyperscale solutions.