| Zettaoctets (Zo) | Zebioctets (Zio) |
|---|---|
| 1 Zettaoctet | 0.847032947254 Zio |
| 2 Zettaoctets | 1.69406589451 Zio |
| 3 Zettaoctets | 2.54109884176 Zio |
| 4 Zettaoctets | 3.38813178902 Zio |
| 5 Zettaoctets | 4.23516473627 Zio |
| 10 Zettaoctets | 8.47032947254 Zio |
| 20 Zettaoctets | 16.9406589451 Zio |
| 25 Zettaoctets | 21.1758236814 Zio |
| 50 Zettaoctets | 42.3516473627 Zio |
| 100 Zettaoctets | 84.7032947254 Zio |
| Reference | Zettaoctets (Zo) | Zebioctets (Zio) |
|---|---|---|
| A plain text message (160 characters) | 1.6 × 10-19 Zo | 1.35525 × 10-19 Zio |
| A three-minute MP3 | 3 × 10-15 Zo | 2.5411 × 10-15 Zio |
| A smartphone photo | 4 × 10-15 Zo | 3.38813 × 10-15 Zio |
| A high-definition film | 4 × 10-12 Zo | 3.38813 × 10-12 Zio |
| A dual-layer Blu-ray disc | 5 × 10-11 Zo | 4.23516 × 10-11 Zio |
The zettaoctet is a unit of digital information equal to a thousand exaoctets, or a sextillion octets. Its symbol is Zo. It is the unit in which the total quantity of data in the world is now described, and the only data unit that has given its name to an era.
That name came from the phrase the zettabyte era, used from around 2016, when annual global internet traffic first exceeded one zettaoctet. Estimates of the global datasphere — every file stored anywhere, plus everything created and immediately discarded — passed a hundred zettaoctets a few years later and continue to rise by tens of zettaoctets a year.
Understanding what these figures include matters more than the numbers themselves. They count copies. A single photograph on a phone is also on the phone's backup, on two servers in a cloud provider's data centre, in a caching layer, and possibly in a machine learning training set. Counting stored octets rather than distinct works inflates the total by a large factor that nobody has ever measured precisely.
The composition of the total is dominated by things nobody looks at. Surveillance and security video, most of it overwritten within weeks, is the single largest category. Sensor and telemetry data from industrial equipment, vehicles and buildings is second. Human-authored material of any kind is a minority, and text is a rounding error within that minority.
Manufacturing sets a hard limit on the total. All the world's storage factories together produce a few hundred exaoctets of new capacity per year, which is a fraction of a zettaoctet, so most data created is never stored at all. It is processed as it arrives and thrown away, and this is a deliberate design choice rather than a failure.
For a sense of the scale, a zettaoctet would be about eight thousand million large consumer hard drives, or roughly one for every person on Earth. Stacked flat, that many drives would form a column reaching well beyond the Moon. The unit describes a quantity that only exists as a sum across a whole planet's industry.
One zettaoctet equals 1,000 exaoctets, 1,000,000,000,000 gigaoctets, 8 zettabits, or about 0.8470 zebioctets.
The zebioctet is a unit of digital information equal to two to the seventieth power octets, which is 1,024 exbioctets. Its symbol is Zio. It is the binary counterpart of the zettaoctet, and the two differ by 18.1 per cent.
Nothing of this size exists. The total quantity of data held by humanity, counting every copy and every backup, is estimated in the low hundreds of zettaoctets, and a zebioctet is 1.18 zettaoctets, so the world holds a few hundred of these units in total. It is the first binary unit for which the world's entire stock is a small multiple rather than a large one.
The unit is defined for completeness rather than for use, which is a deliberate feature of both the metric and the IEC systems. Every prefix applies to every unit without exception, so a reader who has never seen Zio can decode it from the prefix alone. A system that ran out of names at some arbitrary point would force each future user to invent an extension, and rival extensions are how ambiguity is born.
There is one place where the unit would arise naturally. Storage addressing beyond 64 bits has been designed but not needed: the ZFS filesystem uses 128-bit block pointers, giving it a theoretical capacity far beyond any binary prefix that has a name. Where such a scheme states intermediate limits, those limits fall in this range and are properly written in zebioctets.
The 18.1 per cent gap between zebioctet and zettaoctet is worth holding in mind when reading forecasts. Predictions of global data growth are published in zettaoctets, and any that were computed in binary and reported in decimal are nearly a fifth off. Given that such forecasts are already rough, that error is not the largest source of uncertainty, but it is an avoidable one.
The symbol Zio, like all the IEC symbols, is a capital letter followed by lowercase i and then the unit. It is the presence of that i, rather than any statement in the text, that tells a reader unambiguously which quantity is meant, and a document that omits it has not said what it appears to have said.
One zebioctet equals 1,024 exbioctets, 1,180,591,620,717,411,303,424 octets, 8 zebibits, or about 1.181 zettaoctets.