Kioxia and Dell have fit 640 solid-state drives into one standard server rack, which adds up to just over 157 petabytes of storage in a single cabinet.
The Kioxia press release called the build "a new storage density milestone." It uses 16 Dell PowerEdge R7725xd servers, each holding 40 Kioxia LC9 Series enterprise SSDs at 245.76 TB apiece. That works out to about 9.8 petabytes per server and 157.3 petabytes (roughly 157 million gigabytes) across an industry-standard 42U rack. The "U" is a rack unit, a measure of vertical space, and 42U is the common full-height size.
The pitch is aimed at AI data centers. According to the press release, AI workloads are driving growth in unstructured data (files such as video, images and text, as opposed to neat database rows), so organizations need "higher capacity without a corresponding increase in data center floor/rack space, power consumption or cooling requirements." Those are Kioxia's claims about what high-capacity drives can do, and the press release is the source of them.
The space argument is the credible part. Fewer racks per petabyte means less building, and large data center projects are drawing local pushback in several places.
The density gain is about footprint, though, not flash. Every one of those petabytes still needs NAND chips, the memory that SSDs are built from, and consumers are currently paying high prices for SSDs during a NAND shortage. For scale, a single 245.76 TB drive holds as much as 122 consumer drives of 2 TB. The full rack equals about 78,600 of them.