Conversion from Zettaoctets per second to Octets per second

Information about the Zettaoctet per second (Zo/s)

The zettaoctet per second is a unit of data transfer rate equal to a thousand exaoctets per second, or eight zettabits per second. Its symbol is Zo/s. A link running at this rate would transfer everything humanity has ever stored in well under a second, which is the clearest way to state how far beyond present engineering it lies.

The comparison is worth making carefully. Estimates of the world's total stored data run to a few hundred zettaoctets, so a zettaoctet per second would move all of it in a few minutes at most, and a substantial fraction of it every second. Nothing could produce data at that rate and nothing could store it, so the unit describes a capacity with no possible source and no possible destination.

Energy is the constraint that makes this more than a matter of engineering effort. Transmitting a bit costs energy — in the optics, in the electronics that drive them, and in the cooling that removes the waste heat. Current optical systems use on the order of a picojoule per bit end to end. At a zettaoctet per second, that works out to gigawatts of continuous power for the link alone, which is the output of several large power stations.

That figure is not a hard physical limit but an engineering one, and it has fallen steadily. The energy cost per bit of optical transmission has dropped by orders of magnitude over forty years and continues to fall. The theoretical floor, set by thermodynamics, is far lower still, so the obstacle is technique rather than physics.

The unit's practical role is in the completeness of the prefix system rather than in any application. A table of transfer rates that stops before zetta would force anyone who needed it to invent a name, and competing invented names are how measurement systems fragment. Defining the whole ladder costs nothing and prevents that.

For a converter, the arithmetic is the same as for any other prefix: a zettaoctet per second is eight zettabits per second, a thousand exaoctets, and a million petaoctets. The rule does not change because the quantity is unattainable.

One zettaoctet per second equals 1,000 exaoctets per second, 8 zettabits per second, or about 0.8470 zebioctets 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.