Conversion from Yottabits per second to Teraoctets per second

Information about the Yottabit per second (Ybit/s)

The yottabit per second is a unit of data transfer rate equal to a thousand zettabits per second. Its symbol is Ybit/s. For thirty years it was the largest rate the metric system could name, and it describes a speed that has no application anywhere: not in engineering, not in research, and not in any forecast that anyone takes seriously.

Its distance from reality is easy to state. Global internet traffic averages roughly one exabit per second, so a yottabit per second is about a million times the combined communication of the entire human species. The largest single link ever built runs at a few hundred terabits per second, which is a ten-billionth of this figure.

The unit is nonetheless properly defined, and that completeness is the point. The metric system's rule is that every prefix combines with every unit without exception, so a reader who has never seen Ybit/s can decode it from the prefix alone. A system with gaps would need a table of which combinations are legal, and a table is exactly what a rule-based system exists to avoid.

There is a physical way to think about the number. A yottabit per second is 125 zettaoctets per second, and the total quantity of data humanity has ever stored is a few hundred zettaoctets. A link at this rate would therefore transmit the entire accumulated information of the species in a couple of seconds. No such body of data exists in one place to be sent, and nothing at the far end could receive it.

The prefix yotta was adopted in 1991 alongside zetta, at a conference that also had to consider which letters remained free. It stood at the top of the metric ladder until 2022, when ronna and quetta were added above it, partly because data quantities were beginning to approach the old ceiling. Rates have not followed quantities upward at the same pace.

For a converter, handling the unit is a matter of consistency rather than utility. A tool that converts every metric prefix correctly does not need to decide which of them anyone will use, and a figure written in yottabits per second — however unlikely — converts by the same rule as any other.

One yottabit per second equals 1,000 zettabits per second, 125 zettaoctets per second, or about 0.8272 yobibits per second.

Information about the Teraoctet per second (To/s)

The teraoctet per second is a unit of data transfer rate equal to a thousand gigaoctets per second, or eight terabits per second. Its symbol is To/s. It describes memory bandwidth inside the fastest processors and the aggregate throughput of large computing systems, rather than any link between separate machines.

Graphics and accelerator chips are the clearest example. A modern accelerator uses stacked memory placed alongside the processor on the same package, and the bandwidth between them reaches several teraoctets per second. That figure is what allows thousands of arithmetic units to be kept busy at once, and it is now the property that most often determines how fast a machine learning workload runs.

The reason bandwidth rather than arithmetic has become the limiting factor is worth stating. Processors have grown far faster at computing than memory has at supplying data, so a modern chip can perform tens of operations for every octet it reads. Any calculation that touches memory more often than that is limited by the memory, and most real calculations are.

Supercomputer interconnects reach this range in aggregate. The network joining thousands of nodes carries teraoctets per second across the whole machine, though no single link does. The design problem is to arrange the topology so that any node can reach any other quickly, which is why these networks are built as multi-dimensional meshes and trees rather than as simple stars.

To make the number concrete, one teraoctet per second would fill a large consumer hard drive in twenty seconds and transfer the entire text of every book in a national library within a minute. Nothing in ordinary use approaches it, and no external cable of any kind carries it.

The unit also appears in descriptions of storage arrays. A large parallel filesystem, spread across thousands of drives, can deliver a few teraoctets per second in aggregate to a supercomputer, and that figure is quoted as a headline specification because it determines how quickly a simulation can be written out and read back.

One teraoctet per second equals 1,000 gigaoctets per second, 8 terabits per second, or about 0.9095 tebioctets per second.