digitalPhant0m writes to tell us that IBM researchers have set a new world record for areal data density on linear magnetic tape, weighing in at around 29.5 billion bits per square inch. This achievement is roughly 39 times the density of current industry standard magnetic tape. "To achieve this feat, IBM Research has developed several new critical technologies, and for the past three years worked closely with FUJIFILM to optimize its next-generation dual-coat magnetic tape based on barium ferrite (BaFe) particles. [...] These new technologies are estimated to enable cartridge capacities that could hold up to 35 trillion bytes (terabytes) of uncompressed data. This is about 44 times the capacity of today's IBM LTO Generation 4 cartridge. A capacity of 35 terabytes of data is sufficient to store the text of 35 million books, which would require 248 miles (399 km) of bookshelves."