Conversion from 2 Gigaoctets per second to Octets per second

Information about the Gigaoctet per second (Go/s)

The gigaoctet per second is a unit of data transfer rate equal to one thousand million octets per second, or eight gigabits per second. Its symbol is Go/s. It is the unit of the fastest storage devices and of the buses inside a computer, where data moves between processor, memory and drive.

Solid-state drives on the current interface reach 3 to 14 gigaoctets per second, depending on the number of lanes they use and the generation of the bus. Each lane of the peripheral interconnect provides roughly 2 gigaoctets per second at the current generation, and a drive typically uses four of them. Doubling the generation doubles the rate, which is why the figures have risen so steadily.

Main memory is faster still. A modern memory channel delivers 30 to 60 gigaoctets per second, and a machine with several channels reaches hundreds. Graphics processors, which must feed thousands of arithmetic units at once, use memory with bandwidths measured in thousands of gigaoctets per second, at which point the unit gives way to teraoctets.

That hierarchy is what determines how a program performs. A processor can execute far more operations per second than memory can supply data for, so most fast software is written to keep data in the small fast caches rather than to fetch it repeatedly from main memory. The whole discipline of performance engineering rests on the size of these differences.

For everyday comparison, one gigaoctet per second copies a two-gigaoctet film in two seconds, and fills a one-teraoctet drive in about seventeen minutes. That is faster than the network in almost every home and faster than most external connections, so at this rate the bottleneck moves back to whatever is at the other end.

The unit also describes network links in the data centre. A ten-gigabit connection is 1.25 gigaoctets per second, a hundred-gigabit connection 12.5, and both are common between servers. Comparing a storage figure in octets with a network figure in bits requires the factor of eight, and forgetting it is how equipment gets mismatched.

One gigaoctet per second equals 1,000,000,000 octets per second, 8 gigabits per second, or about 0.9313 gibioctets per second.

Information about the Octet per second (octet/s)

The octet per second is a unit of data transfer rate equal to eight bits per second. Its symbol is octet/s. It is the unit in which software reports transfer speeds, as against the bits per second in which hardware and network services advertise them, and the factor of eight between the two conventions is the source of endless confusion.

The division of labour is consistent once it is understood. Anything describing a physical link — an Ethernet port, a fibre connection, a radio channel, a broadband package — is quoted in bits per second, because bits are what the signalling actually carries. Anything describing a file moving from one place to another is quoted in octets per second, because files are measured in octets.

A download manager that reports 12 megaoctets per second on a connection sold as 100 megabits per second is not disagreeing with the advertisement; it is stating the same rate in the other convention, and the arithmetic between them is a division by eight. Recognising this immediately removes the most common cause of complaint about internet speed.

Individual octets per second appear in the same narrow places as individual bits: deep-space telemetry, low-power sensor links, and the slowest legacy serial connections. A rate of a hundred octets per second would move a page of text in about twenty seconds, which was a normal experience in the 1970s and is unimaginable now.

The unit also underlies the way disc and interface throughput is described. A drive that sustains 500 megaoctets per second is moving four gigabits per second across its interface, and matching the two figures is a routine part of system design: an interface rated in gigabits must be compared with a drive rated in octets, and the factor of eight decides whether one starves the other.

Storage tools reinforce the convention. Every file copy utility, backup program and command-line transfer tool reports in octets per second or its multiples, and every network measurement tool reports in bits per second. A person reading both at once has to keep the conversion in mind, which is exactly what makes the distinction worth stating explicitly.

One octet per second equals 8 bits per second, 0.008 kilobits per second, or 0.001 kilooctets per second.