| Petaoctets (Po) | Mebibits (Mibit) |
|---|---|
| 1 Petaoctet | 7629394531.25 Mibit |
| 2 Petaoctets | 15258789062.5 Mibit |
| 3 Petaoctets | 22888183593.8 Mibit |
| 4 Petaoctets | 30517578125 Mibit |
| 5 Petaoctets | 38146972656.2 Mibit |
| 10 Petaoctets | 76293945312.5 Mibit |
| 20 Petaoctets | 152587890625 Mibit |
| 25 Petaoctets | 190734863281 Mibit |
| 50 Petaoctets | 381469726562 Mibit |
| 100 Petaoctets | 762939453125 Mibit |
| Reference | Petaoctets (Po) | Mebibits (Mibit) |
|---|---|---|
| A plain text message (160 characters) | 1.6 × 10-13 Po | 0.0012207 Mibit |
| A three-minute MP3 | 0.000000003 Po | 22.8882 Mibit |
| A smartphone photo | 0.000000004 Po | 30.5176 Mibit |
| A high-definition film | 0.000004 Po | 30517.6 Mibit |
| A dual-layer Blu-ray disc | 0.00005 Po | 381470 Mibit |
The petaoctet is a unit of digital information equal to a thousand teraoctets, or a million gigaoctets. Its symbol is Po. It is the unit of institutional storage: the scale at which data belongs to an organisation rather than to a person, and at which keeping it becomes a budget line rather than an afterthought.
A petaoctet is roughly the storage of a thousand large consumer hard drives, or the text of every book ever published several times over. In video terms it is about twenty thousand hours in ultra-high definition, or two and a half years of continuous viewing. The entire catalogue of a large streaming service, held once at each quality level, comes to a few petaoctets.
Science reached this scale first. The Large Hadron Collider at CERN records tens of petaoctets a year after its trigger systems have already discarded more than 99.99 per cent of what the detectors see, and the full archive runs to several hundred petaoctets. Astronomy, genomics and climate modelling all keep archives of comparable size, and the discipline of managing them became a research field of its own.
Commercially the petaoctet describes a single data centre's storage rather than a company's total. A large organisation holds tens or hundreds of petaoctets across many sites, and the largest cloud providers hold exaoctets. At this size the practical problems are not capacity but the electricity to keep the drives spinning, the cooling, and the certainty that a fraction of the hardware is failing at any moment.
That last point drives the design. In a petaoctet array, drive failures are not exceptional events but a continuous background rate, so the system is built to lose devices constantly and rebuild without interruption. Data is stored with erasure coding across many machines, and no single copy of anything is trusted.
Reading a petaoctet is itself a problem. Even at ten gigaoctets per second, a rate few systems sustain, a full pass takes more than a day. This is why analysis at this scale is designed to move the computation to the data rather than the data to the computation, an inversion that shaped the whole field of distributed processing.
One petaoctet equals 1,000 teraoctets, 1,000,000 gigaoctets, 8 petabits, or about 0.8882 pebioctets.
The mebibit is a unit of digital information equal to 1,048,576 bits, which is 1,024 kibibits or two to the twentieth power. Its symbol is Mibit. It is the binary counterpart of the megabit, and the difference between the two has grown to 4.9 per cent — small enough to be ignored casually, large enough to matter in a specification.
Its natural home is semiconductor memory, where capacity is fixed by the address lines on the chip. A memory die with twenty address bits can reach exactly 1,048,576 locations, so densities land on powers of two rather than on round decimal numbers. A chip described as 512 megabits in a catalogue is very often 512 mebibits in reality, which is 537 megabits, and the datasheet is where the truth is written.
That habit is old and deliberate. Semiconductor manufacturers have always sized memory in binary because the wiring makes any other choice wasteful: an address bus is a fixed number of lines, and using only part of the range it can reach throws away silicon. Storage manufacturers had no such constraint, which is precisely why the two industries diverged.
For a sense of quantity, a mebibit is 131,072 octets, or about 128 kibioctets. That is roughly the contents of a long book as plain text, or a single low-resolution image. In network terms it is a hundredth of a second of a gigabit link.
The IEC prefixes were introduced in 1998 partly because at this level and above the approximation stops being safe. Buying a component described as one megabit and receiving one mebibit is a five per cent surprise; at the tebibit the same confusion is a ten per cent surprise, and in a contract for a data centre that is a real sum of money.
Correct usage is now common in standards documents, in hardware datasheets and in operating system internals, and rare in advertising and consumer software. The best rule when reading a figure is to ask which industry produced it: if it describes memory or a chip, assume binary; if it describes storage or a link, assume decimal.
One mebibit equals 1,048,576 bits, 1,024 kibibits, 131,072 octets, or about 1.049 megabits.