| Zettaoctets (Zo) | Teraoctets (To) |
|---|---|
| 1 Zettaoctet | 1000000000 To |
| 2 Zettaoctets | 2000000000 To |
| 3 Zettaoctets | 3000000000 To |
| 4 Zettaoctets | 4000000000 To |
| 5 Zettaoctets | 5000000000 To |
| 10 Zettaoctets | 10000000000 To |
| 20 Zettaoctets | 20000000000 To |
| 25 Zettaoctets | 25000000000 To |
| 50 Zettaoctets | 50000000000 To |
| 100 Zettaoctets | 100000000000 To |
| Reference | Zettaoctets (Zo) | Teraoctets (To) |
|---|---|---|
| A plain text message (160 characters) | 1.6 × 10-19 Zo | 1.6 × 10-10 To |
| A three-minute MP3 | 3 × 10-15 Zo | 0.000003 To |
| A smartphone photo | 4 × 10-15 Zo | 0.000004 To |
| A high-definition film | 4 × 10-12 Zo | 0.004 To |
| A dual-layer Blu-ray disc | 5 × 10-11 Zo | 0.05 To |
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 teraoctet is a unit of digital information equal to one million million octets, or a thousand gigaoctets. Its symbol is To. It is the unit of the modern hard drive, and the point at which personal storage stopped being something anyone needed to manage carefully.
A teraoctet holds roughly two hundred and fifty thousand photographs from a phone, or two hundred hours of high-definition video, or a quarter of a million songs. For a person who is not a professional photographer or video editor, a single teraoctet is more storage than a lifetime of ordinary files will fill.
Consumer hard drives crossed one teraoctet in 2007 and now reach twenty or more. Solid-state drives arrived at the same capacities more slowly and at higher cost, but with far greater speed, and the two technologies now divide the market between capacity and performance rather than competing directly.
The teraoctet is where the decimal-binary discrepancy becomes visible enough to annoy. A drive sold as one teraoctet holds a million million octets exactly; the operating system divides by 1,024 four times and reports 0.909 tebioctets, which it usually labels as 931 gigaoctets. The shortfall appears to be 7 per cent, though nothing has actually been lost. At the petaoctet the same arithmetic produces a 12 per cent gap.
Backup and archiving live at this scale. A household's complete collection of photographs, documents and video typically fits in a few teraoctets, which is why external drives are sold in exactly that range. Cloud storage services price in teraoctets too, and the economics of keeping a second copy of everything only work because the unit price of storage has fallen faster than the quantity has grown.
In professional work the teraoctet is a daily quantity rather than a milestone. A day of filming in high resolution produces several teraoctets of raw footage. A genome sequencing run produces a few hundred gigaoctets, so a modest laboratory generates teraoctets a week. Both fields have had to build workflows around moving data that will not fit on any network in reasonable time.
One teraoctet equals 1,000,000,000,000 octets, 1,000 gigaoctets, 8 terabits, or about 0.9095 tebioctets.