Comment on What the Hell is this Bull shit ?
black0ut@pawb.social 6 days agoThere are (mainly) 3 reasons for that:
TB vs TiB: Computers don’t count drive space in metric units, they count it in powers of 2. This means that, for you, 1 TB is 1000 GB, while for a computer, 1 TiB is 1024 GiB. Drive manufactirers take advantage of this, and only count space in metric (TB). So when you plug the drive into your computer, and it converts to GiB, you end up with 1 TB = 931.3 GiB. Windows hasn’t helped this confusion, I remember it doing something weird like counting in GiB and displaying it as GB.
Reserved space: Many OSes reserve some space on their drives for special stuff. This is especially the case with Linux and ext4, where it by default reserves a percentage of the drive to root. This is to optimize distribution of files around the disk, which limits fragmentation. The system slowly frees more of this space as you fill up the disk, and at the end it should leave you with 100% of the space.
Formatting: Empty drive space isn’t the same as usable drive space. In order to use a drive you need to format it, which doesn’t just blank it. Formatting a drive adds a filesystem to it, which is what allows you to write files and folders to it. This filesystem takes up some space, and reserves more space for inodes and, in some cases, a filesystem journal. Some filesystems have even more features that also take up some space.
This has nothing to do with metric. There was just a tradition to use the SI prefixes in binary and with k/K it worked. With MB it doesn’t work that well anymore, which is why they came up with MiB at some point, but MB can still be interpreted binary like it always was. Software can often display both binary and decimal prefixes. There are also different standards how to handle these units for different kinds of storage.
1kB is clearly 1000B and 1KB is clearly 1024B
All software has always interpreted it in binary as far as I know. There never was a good standard, and the most common way to differentiate in my experience was using KB as metric (decimal, SI) and K as binary. It’s easy to confuse with the already convoluted standard of KB being a kilobyte and Kb being a kilobit.
The reason for the added “i” is that in every other system, kilo means 1000. Someone at the SI realized that it didn’t make any sense to have it mean something different in software so they invented the Ki prefix (instead of K) to mean 1024. That is now the standard, and it’s part of the SI (coloquially metric). As a consequence of this, you can technically use the Ki prefix with any other SI unit, so you can also use the KiM (kibimeter), which is 1024 meters. Idk why you’d use it, but it’s funny that the option exists.
using KB as metric (decimal, SI) and K as binary.
Kilo has to be lower case, so it should be kB for decimal kilobyte. All SI prefixes are case sensitive. Kilo, hecto and deca are weird outliers since they are all written lower case, otherwise SI uses uppercase for prefixes larger than factor one and lower case for those smaller. I know people often don’t pay that much attention to that for bytes since there is nothing smaller than a bit.
There is a huge difference between 5mm and 5Mm. 5Mm = 5000000000mm
With other prefixes it gets even more extreme:
JcbAzPx@lemmy.world 6 days ago
GB to measure binary gigabytes came first. GiB was invented because advertisers and drive manufacturers are evil.
black0ut@pawb.social 6 days ago
GiB weren’t invented by drive manufacturers (although they definitely benefit from it, and are incredibly scummy about it). It was invented by the SI people. GiB make sense, because the prefix “Giga” means 10⁶, while in binary it meant 2²⁰. It was a mess before, and GiB just standardized it in a way that is easy to understand and consistent with other units.
I do think we should force drive manufacturers to express their drive capacity in binary format, tho.
JcbAzPx@lemmy.world 5 days ago
Right, in response to drive manufacturers using GB incorrectly.