| Exbibits per second (Eibit/s) | Teraoctets per second (To/s) |
|---|---|
| 1 Exbibit per second | 144115.188076 To/s |
| 2 Exbibits per second | 288230.376152 To/s |
| 3 Exbibits per second | 432345.564228 To/s |
| 4 Exbibits per second | 576460.752303 To/s |
| 5 Exbibits per second | 720575.940379 To/s |
| 10 Exbibits per second | 1441151.88076 To/s |
| 20 Exbibits per second | 2882303.76152 To/s |
| 25 Exbibits per second | 3602879.7019 To/s |
| 50 Exbibits per second | 7205759.40379 To/s |
| 100 Exbibits per second | 14411518.8076 To/s |
| Reference | Exbibits per second (Eibit/s) | Teraoctets per second (To/s) |
|---|---|---|
| A dial-up modem | 4.85723 × 10-14 Eibit/s | 0.000000007 To/s |
| Typical home broadband | 8.67362 × 10-11 Eibit/s | 0.0000125 To/s |
| Gigabit Ethernet | 8.67362 × 10-10 Eibit/s | 0.000125 To/s |
| Streaming a 4K film | 2.1684 × 10-11 Eibit/s | 0.000003125 To/s |
The exbibit per second is a unit of data transfer rate equal to two to the sixtieth power bits per second, which is 1,024 pebibits per second. Its symbol is Eibit/s. It is the binary counterpart of the exabit per second, and the two differ by 15.3 per cent.
That fifteen per cent is more than the margin most engineering work allows anywhere. A quantity stated in the wrong convention at this level is not slightly imprecise but plainly wrong, and no amount of context recovers the intended figure once it has been written ambiguously. This is the situation the IEC prefixes were introduced to prevent.
No physical link approaches this rate. The unit describes aggregates: the total instantaneous traffic of the whole internet is roughly an exabit per second, so a binary exbibit per second is fifteen per cent more than everything moving on every network on the planet at a given moment.
Where a binary figure of this size arises naturally is in address arithmetic rather than in transmission. Two to the sixtieth is a number that appears throughout the design of 64-bit systems, and any rate derived from filling or traversing such an address space in a fixed time is naturally binary. Those calculations are theoretical, but they are the reason the unit is defined rather than left unnamed.
In octets an exbibit per second is 144,115,188,075,855,872, or 128 pebioctets per second. That is more storage moved per second than the world manufactures in several years, which is a way of saying that no source and no destination for such a flow could exist.
For a converter the treatment is mechanical and must be exact. Eibit/s and Ebit/s differ by an eighth, and a tool that treats them as interchangeable has introduced an error larger than the difference between many neighbouring units. The lowercase i is not decoration.
One exbibit per second equals 1,024 pebibits per second, 144,115,188,075,855,872 octets per second, or about 1.153 exabits per second.
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.