| Pebioctets (Pio) | Petabits (Pbit) |
|---|---|
| 1 Pebioctet | 9.00719925474 Pbit |
| 2 Pebioctets | 18.0143985095 Pbit |
| 3 Pebioctets | 27.0215977642 Pbit |
| 4 Pebioctets | 36.028797019 Pbit |
| 5 Pebioctets | 45.0359962737 Pbit |
| 10 Pebioctets | 90.0719925474 Pbit |
| 20 Pebioctets | 180.143985095 Pbit |
| 25 Pebioctets | 225.179981369 Pbit |
| 50 Pebioctets | 450.359962737 Pbit |
| 100 Pebioctets | 900.719925474 Pbit |
| Reference | Pebioctets (Pio) | Petabits (Pbit) |
|---|---|---|
| A plain text message (160 characters) | 1.42109 × 10-13 Pio | 1.28 × 10-12 Pbit |
| A three-minute MP3 | 0.00000000266454 Pio | 0.000000024 Pbit |
| A smartphone photo | 0.00000000355271 Pio | 0.000000032 Pbit |
| A high-definition film | 0.00000355271 Pio | 0.000032 Pbit |
| A dual-layer Blu-ray disc | 0.0000444089 Pio | 0.0004 Pbit |
The pebioctet is a unit of digital information equal to 1,125,899,906,842,624 octets, which is 1,024 tebioctets. Its symbol is Pio. It is the binary counterpart of the petaoctet, and the two now differ by 12.6 per cent.
This is the unit in which filesystem limits are written. Several widely deployed filesystems have maximum file or volume sizes that are exact powers of two, and those limits fall in this range: sixteen tebioctets for one, a pebioctet for another, eight pebioctets for a third. The numbers are not choices made by anyone; they follow from how many bits the filesystem uses to number its blocks.
Large scientific and commercial storage systems are also sized here. A research computing centre may run a filesystem of several pebioctets across thousands of drives, and the tools that manage it report in pebioctets because the underlying allocation is binary throughout. Converting those figures to decimal units for a report introduces an error of an eighth for no benefit.
A pebioctet is roughly a thousand large consumer hard drives, or the complete video output of a broadcaster over many years. It is also close to the size of the largest single scientific archives, though those are typically stated in petaoctets by press offices and in pebioctets by the engineers who run them, which produces two different numbers for the same building.
Distinguishing the two is not pedantry at this level. A twelve per cent difference on a purchase of many pebioctets is a large sum of money, and a capacity plan built on the wrong unit will be wrong by more than the margin most plans allow. This is precisely the situation the IEC prefixes were introduced to prevent.
The symbol Pio is used in filesystem documentation, in storage system manuals and in standards. Where a source writes PB without saying which it means, the difference is an eighth, and the honest thing for a reader to do is treat the figure as approximate rather than assume one convention or the other.
One pebioctet equals 1,024 tebioctets, 1,125,899,906,842,624 octets, 8 pebibits, or about 1.126 petaoctets.
The petabit is a unit of digital information equal to a thousand terabits, or a million billion bits. Its symbol is Pbit. It sits at the boundary between quantities that are routinely deployed and quantities that still belong to research laboratories and to totals aggregated across whole networks.
A petabit is 125 teraoctets. That is the storage of roughly a hundred and twenty-five large consumer hard drives, or in more everyday terms about thirty thousand hours of high-definition video — three and a half years of continuous viewing. No single device holds a petabit; the figure describes systems rather than objects.
The most striking use of the unit is in optical transmission records. Research groups in Japan, the Netherlands and elsewhere have carried more than a petabit per second down a single strand of fibre, achieved by combining multi-core fibre — several light-guiding paths inside one cladding — with hundreds of separate wavelengths and advanced modulation. Those results run over tens of kilometres in the laboratory, not the thousands of kilometres a working sea cable must cross.
At the network level the petabit describes aggregate capacity. The total interconnect capacity of a large data centre, the combined capacity of all cables landing on a continent, and the peak throughput of the largest content networks are all quoted in petabits per second. These are sums over many links rather than the rating of any one of them.
Storage systems reach petabit scale too, though they are always labelled in octets. A large scientific archive holding a hundred petaoctets is holding eight hundred petabits, and facilities of that size exist for genomics, particle physics and astronomical survey data. The particle detectors at CERN discard the vast majority of what they see precisely because keeping it would exceed even these capacities.
The prefix peta comes from the Greek for five, because a petabit is a thousand raised to the fifth power in bits. That naming pattern continues upward with exa for six and zetta for seven, so the ladder above the petabit is regular and easy to extend.
One petabit equals 1,000,000,000,000,000 bits, 1,000 terabits, 125 teraoctets, or about 0.8882 pebibits.