| Pebioctets (Pio) | Exbibits (Eibit) |
|---|---|
| 1 Pebioctet | 0.0078125 Eibit |
| 2 Pebioctets | 0.015625 Eibit |
| 3 Pebioctets | 0.0234375 Eibit |
| 4 Pebioctets | 0.03125 Eibit |
| 5 Pebioctets | 0.0390625 Eibit |
| 10 Pebioctets | 0.078125 Eibit |
| 20 Pebioctets | 0.15625 Eibit |
| 25 Pebioctets | 0.1953125 Eibit |
| 50 Pebioctets | 0.390625 Eibit |
| 100 Pebioctets | 0.78125 Eibit |
| Reference | Pebioctets (Pio) | Exbibits (Eibit) |
|---|---|---|
| A plain text message (160 characters) | 1.42109 × 10-13 Pio | 1.11022 × 10-15 Eibit |
| A three-minute MP3 | 0.00000000266454 Pio | 2.08167 × 10-11 Eibit |
| A smartphone photo | 0.00000000355271 Pio | 2.77556 × 10-11 Eibit |
| A high-definition film | 0.00000355271 Pio | 0.0000000277556 Eibit |
| A dual-layer Blu-ray disc | 0.0000444089 Pio | 0.000000346945 Eibit |
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 exbibit is a unit of digital information equal to two to the sixtieth power bits, which is 1,024 pebibits. Its symbol is Eibit. It is the binary counterpart of the exabit, and the two now differ by 15.3 per cent.
Two to the sixtieth is a number with a particular importance in computing, because sixty is close to the sixty-four bits of a modern processor address. A 64-bit machine can address sixteen exbioctets of memory, and that figure — 16 EiB — is the theoretical ceiling of the entire architecture. It appears in processor manuals, in operating system documentation and in the specification of every 64-bit filesystem.
No machine comes close to using that range. Current processors implement only forty-eight or fifty-seven of those sixty-four address bits, because wiring the full width would cost silicon for an address space nobody can fill. The unused bits are reserved, and widening the implementation is a straightforward matter whenever memory sizes make it worthwhile, which is the point of having chosen sixty-four in the first place.
An exbibit is 144,115,188,075,855,872 octets, or 128 pebioctets. That is more storage than any single organisation holds, and comparable to the combined annual output of a large part of the storage industry. As with all the larger binary units, it describes limits and capacities in specifications rather than anything that has been built.
The unit is also where filesystem designers set their maximum sizes. Filesystems built around 64-bit block pointers naturally have limits at exact powers of two, and several widely deployed ones specify maximum volume sizes in exbioctets. Those numbers are not aspirations; they are the arithmetic consequence of the pointer width, and they will hold until the architecture changes.
Reading the symbol correctly matters here. Eibit is the exbibit; Ebit is the exabit; EB and EiB are the octet forms of each. In a document where a fifteen per cent difference is significant — and at this scale it always is — the presence or absence of the lowercase i carries the entire meaning.
One exbibit equals 1,024 pebibits, 144,115,188,075,855,872 octets, or about 1.153 exabits.