Conversion from Zettaoctets per second to Megaoctets 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 Megaoctet per second (Mo/s)

The megaoctet per second is a unit of data transfer rate equal to one million octets per second, or eight megabits per second. Its symbol is Mo/s. It is the unit in which storage devices and their interfaces are rated, and the one a file manager shows while a copy is running.

Storage speeds fall naturally into this range. A mechanical hard drive sustains 100 to 250 megaoctets per second on sequential reads. A solid-state drive on the older interface reaches about 550, which is the limit of that interface rather than of the drive. A modern drive on the faster interface reaches several thousand, at which point the unit gives way to gigaoctets per second.

Interface speeds tell the same story from the other side. The successive versions of the universal serial bus have offered roughly 1.5, 60, 625 and 2,500 megaoctets per second at their nominal rates, and memory card standards have followed a similar path. A device is always limited by whichever of the two is slower, and matching them is the practical art of building a fast system.

For everyday sizes, one megaoctet per second transfers a photograph in a couple of seconds and a two-gigaoctet film in about half an hour. At 500 megaoctets per second the same film takes four seconds. That contrast explains why the perceived speed of a computer changed so completely when solid-state storage replaced mechanical drives, even though processors improved far less over the same period.

Sequential rates like these are the best case. Reading many small files instead of one large one costs far more, because each file requires locating its data and reading its record. A drive that sustains 500 megaoctets per second in sequence may manage only a few tens when copying a directory of thousands of small files, and that is where the difference between drive technologies is most visible.

The unit also describes the throughput of a busy network connection: a gigabit link delivers 125 megaoctets per second at best, so a fast local network and a fast drive are now comparable, and neither is obviously the limiting factor in a transfer.

One megaoctet per second equals 1,000,000 octets per second, 8 megabits per second, or about 0.9537 mebioctets per second.