Standards: IEC Giga [re: FreeBSD image size confusion]

grarpamp grarpamp at
Sat Mar 13 22:07:04 UTC 2021

> is in true GBs

"true" is not a modifier of any prefix or unit in any standard,
though false GB are what's reported by USB firmware in
cheapo USB drives from some sketchy vendors ;)

> 4.5 GigaBytes means 4.5 GiB.

4500000000 does not equal or "mean" 4831838208.

International Standards IEC (re ISO/SI/Metric)...
"giga" = "G" = decimal prefix, powers of ten, 10^, base 10 underlying
"gibi" = "Gi" = binary prefix, powers of two, 2^, base 2 underlying
There is no such prefix as "K", it's "kilo k" or "kibi Ki".
"B"yte is 8 "b"its.
RAM is in binary 2^.
Physical storage DVD/BR/USB/disk/tape/etc (quotable in decimal 10^
on the box [1]), filesystem and files UI presentation displayable in
binary prefix, use correct underlying math.
Rest in decimal 10^, including...
Network bandwidth rates... routers switches OS interfaces hardware interfacing
upstream, constant bandwidth rate managed network centric app software
overlays, even packet filters]... in [kMGT...]bps ("b"its/sec) ie:
100Mbps, not the "bi"
prefixes, nor even "B"ytes... with counters in bytes not bits.
Contexts pair their associated "prefix, to base unit, to underlying math",
ie: kilometers distance (km) not kibimeters (Kim), mebibytes RAM (MiB)
not megabytes (MB), gigabps network rates (Gbps) with tier level ISPs
not gibibps (Gibps). Silly bytes per period referenced transfer notation
(B/sec, B/day, B/mon) of legacy small webhosters, and phone extortion
billing models, that all calculate and use average bitrate with upstream
already anyway... orthagonal and falling off.

Many areas in FreeBSD could be checked for representation...
prefixes for disk space using decimal G instead of binary Gi,
places under a given context (netrates or diskspace) but displaying
mixed representations across their respective utilities in base, etc.

Rockets crash due to perpetuating use of nonstandard / mix legacy.
Representations could look towards some newer formal standardization
than pre-2000's adhoc.

Linux seems to making some RAM/disk/netrates updates there with
"bi" prefixes now appearing in various places, do not know if they have
a standards conformance / base policy doc on that.  IEC 80000-13:2008

[1] Pre :2008, WDC and STX lawsuits forced more disclosure and market
still annoying to convert box/nameplate/sector decimal <--> logical binary.

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