Petabit to Exbibyte

One petabit = 10¹⁵ bits = 125 terabytes. To put it in perspective: the entire text content of all English Wikipedia articles is roughly 4 GB — so a petabit could hold about 31,000 copies of it. A petabit per second link could transfer all of Wikipedia's text content in about 32 microseconds.

As of 2024, no single commercial link carries 1 Pbps, but laboratory experiments have demonstrated fiber optic transmission exceeding 1 Pbps using dense wavelength-division multiplexing on a single fiber strand. Commercial submarine cables aggregate hundreds of terabits per second across many fibers and wavelengths, collectively reaching petabit-scale capacity per cable system.

A petabit (Pb) = 10¹⁵ bits. A petabyte (PB) = 10¹⁵ bytes = 8 petabits. Storage systems (data centers, archival systems) use petabytes for capacity; aggregate network throughput uses petabits per second. An exabyte-scale data center stores 1,000 petabytes; its internal network may carry multiple petabits per second of traffic.

Qubits and classical bits solve fundamentally different problems — qubits will not simply replace petabit-scale classical storage or networking. A quantum computer with 1,000 logical qubits can explore 2¹⁰⁰⁰ states simultaneously, but measuring those qubits collapses them to classical bits. Quantum networks will likely handle key distribution and entanglement sharing at kilobit-to-megabit rates, while classical infrastructure continues to move petabits of bulk data. The two technologies are complementary, not substitutional.

Submarine fiber optic cables are built by a handful of companies (SubCom, NEC, Alcatel Submarine Networks) and typically cost $200–500 million per system. A modern cable contains 12–24 fiber pairs, each carrying hundreds of wavelengths via dense wavelength-division multiplexing, reaching 400+ Tbps aggregate capacity per cable. Cables are designed to last 25 years on the ocean floor. When faults occur, specialised cable repair ships (fewer than 60 exist worldwide) locate breaks using optical time-domain reflectometry and splice repairs at sea — a process that can take days to weeks depending on depth and weather.

EB (exabyte) = 10¹⁸ bytes (SI decimal). EiB (exbibyte) = 2⁶⁰ bytes = 1,152,921,504,606,846,976 bytes (IEC binary). EiB is 15.29% larger. This is the largest practically significant SI vs IEC discrepancy: per exbibyte, the binary value exceeds the decimal value by approximately 152,921,504,606,846,976 bytes — about 152.9 petabytes.

One exbibyte (EiB) ≈ 1.153 × 10¹⁸ bytes = 1,073,741,824 GiB = 1,048,576 TiB. In practical terms: enough to store approximately 230 billion JPEG photos at 5 MB each, or 288,230,376 copies of a 4 GB HD movie, or the entire text content of the English internet many thousands of times over.

In theory, yes — and with astonishing density. DNA can encode about 215 PiB per gram of material, meaning a single EiB could fit in roughly 4.7 grams of synthetic DNA. Researchers at Microsoft and the University of Washington have demonstrated writing and reading megabytes of data in DNA strands. The challenges are speed and cost: current DNA synthesis writes about 400 bytes per second and costs around $3,500 per megabyte. At that rate, writing 1 EiB would take billions of years and cost more than global GDP. However, enzymatic synthesis breakthroughs could reduce costs by 6–8 orders of magnitude within decades.

Storing 1 EiB on modern HDDs would require roughly 57,000 drives of 20 TB each, consuming about 400–500 kW of power just for the drives — plus 200–300 kW for cooling, networking, and overhead. That totals roughly 6 GWh per year, equivalent to powering about 550 US homes. At typical US grid carbon intensity, this produces around 2,500 tonnes of CO₂ annually. Hyperscale operators reduce this via renewable energy and immersion cooling, but the fundamental physics of spinning magnetic platters or maintaining NAND charge states sets a floor on energy consumption that no software optimisation can eliminate.

After exbibyte (EiB, 2⁶⁰ bytes) come: zebibyte (ZiB, 2⁷⁰ bytes) and yobibyte (YiB, 2⁸⁰ bytes), as defined in IEC 80000-13. These are recognized standard units but have no current practical applications. The entire global internet's estimated stored data (hundreds of EB) is still in the low hundreds of EiB range — well short of one ZiB.