| Pebioctets per second (Pio/s) | Exaoctets per second (Eo/s) |
|---|---|
| 1 Pebioctet per second | 0.00112589990684 Eo/s |
| 2 Pebioctets per second | 0.00225179981369 Eo/s |
| 3 Pebioctets per second | 0.00337769972053 Eo/s |
| 4 Pebioctets per second | 0.00450359962737 Eo/s |
| 5 Pebioctets per second | 0.00562949953421 Eo/s |
| 10 Pebioctets per second | 0.0112589990684 Eo/s |
| 20 Pebioctets per second | 0.0225179981369 Eo/s |
| 25 Pebioctets per second | 0.0281474976711 Eo/s |
| 50 Pebioctets per second | 0.0562949953421 Eo/s |
| 100 Pebioctets per second | 0.112589990684 Eo/s |
| Reference | Pebioctets per second (Pio/s) | Exaoctets per second (Eo/s) |
|---|---|---|
| A dial-up modem | 6.21725 × 10-12 Pio/s | 7 × 10-15 Eo/s |
| Typical home broadband | 0.0000000111022 Pio/s | 1.25 × 10-11 Eo/s |
| Gigabit Ethernet | 0.000000111022 Pio/s | 1.25 × 10-10 Eo/s |
| Streaming a 4K film | 0.00000000277556 Pio/s | 3.125 × 10-12 Eo/s |
The pebioctet per second is a unit of data transfer rate equal to 1,024 tebioctets per second, or two to the fiftieth power octets per second. Its symbol is Pio/s. It is the binary counterpart of the petaoctet per second, and the two differ by 12.6 per cent.
The rate exists only as a total. The aggregate memory bandwidth of a whole supercomputer, or the summed capacity of the network fabric joining its cabinets, reaches this range, and both are sums over tens of thousands of components, each of which moves a few hundred gibioctets per second on its own.
Whether such a total means anything depends on the calculation being run. A problem that divides so that each node works mostly on its own data can use the full aggregate. A problem where every node must constantly consult every other cannot, and the machine's effective bandwidth falls to what the slowest shared path allows. Most of the art of parallel programming lies in getting problems into the first category.
In octets a pebioctet per second is 1,125,899,906,842,624, and in decimal terms about 1.126 petaoctets per second. The 12.6 per cent difference is the accumulated effect of five multiplications by 1.024, and it is now large enough that no report can leave the convention unstated without introducing real uncertainty.
The unit also appears in descriptions of parallel filesystems at the largest facilities, where a storage system spread across tens of thousands of drives delivers a few pebioctets per second to a compute cluster. That number determines how quickly the machine can checkpoint its state, which in turn determines how much work is lost when a component fails — and in a machine of that size, something is always failing.
For a converter the requirement is simply that the arithmetic be exact and the label preserved. Multiplying by 1,024 five times is not difficult; silently substituting the decimal prefix is the error to avoid.
One pebioctet per second equals 1,024 tebioctets per second, 1,125,899,906,842,624 octets per second, or about 1.126 petaoctets per second.
The exaoctet per second is a unit of data transfer rate equal to a thousand petaoctets per second, or eight exabits per second. Its symbol is Eo/s. Nothing built runs at this rate: it is about eight times the total traffic of the entire internet, counted across every network on the planet at once.
The unit is useful mainly for thought experiments about limits. If every hard drive and flash chip manufactured in a year were read simultaneously at full speed, the combined rate would be in this range. So would the total output of every camera sensor in every phone on Earth if they all recorded at once. These are sums over the whole world's hardware, not rates any system experiences.
There is one situation in which very large data volumes really do move faster than any network, and it puts the unit in perspective. Physically shipping a container of hard drives across an ocean transfers more data per second, averaged over the journey, than any cable. A shipping container holding a few exaoctets crossing the Atlantic in a week works out to several gigaoctets per second, and a truck of drives driven across a city beats almost any local link.
That calculation is not a joke; cloud providers offer it as a service. When a customer needs to move petaoctets into a data centre, the provider ships a lorry full of storage rather than attempting the transfer over a network, because the network would take months. The bandwidth of a vehicle is enormous, though its latency is measured in days.
For the unit itself, an exaoctet per second is 125 petaoctets per second, and it would transfer the world's entire stock of stored data — a few hundred zettaoctets — in about a week of continuous running. No mechanism exists to feed such a link, and none is being designed.
A converter must nevertheless handle the unit, because it appears in aggregate capacity models, in academic papers on the theoretical limits of communication, and in any table that lists the metric prefixes completely. A quantity does not need a use for its name to be well formed.
One exaoctet per second equals 1,000 petaoctets per second, 8 exabits per second, or about 0.8674 exbioctets per second.