[rescue] expanding a ZFS pool: leave slack space?

[Romain Dolbeau]

Le dim. 2 mai 2021 C  02:15, Mouse <mouse at rodents-montreal.org> a C)crit :
> Only for disk-maker-redefined values of "TB".  At least in my
> experience, "4TB" disks are a smidgen under 3.6387 actual TB

'Tera' has meant 10^12 since 1960 (along 'Giga' for 10^9), when the SI
was introduced as an update to the Metric system.
Larger decimal prefixes were introduced up to in 1975 and 1991.

Why would you expect the manufacturer to not comply with a standard in
use in 95+% of the countries in the world?
They're simply using a standard-compliant notation that's easier for
most people than "32*10^12", let alone "3.6387*2^30"

No standard body has ever defined the Tera as anything different from 10^12.

The IES has defined binary prefixes to handle situations where
power-of-2 are useful.
It's very simple to write 32 GiB or 3.64 TiB and be unambiguous.

Sorry for the rant, but it's one of my pet annoyances and I keep
pestering my colleagues to make sure they use standard-compliant units
and prefixes in documentation to make things clear.
When you use 'MiB', 'GiB' or 'Tib' everywhere for memories and caches
and other Po2 structures, the use of 'GB' or 'TB' for storage or 'GHz'
for frequency doesn't raise so many questions.
Different prefixes for different use cases.

For those interested in a bit of history, the BIPM has the older
brochures of the SI online:
<https://www.bipm.org/en/publications/si-brochure>
'Tera' is on page 13 of the 1970 brochure, and at the time was still
the largest SI prefix (negative-power-of-10 prefixes were introduced
sooner as they had more use in physical sciences at the time).

Cordially,

--
Romain Dolbeau