Linked by Thom Holwerda on Fri 19th Oct 2012 20:07 UTC
Windows Interesting little tidbit from the Reddit AMA session with Microsoft's Surface team. One Redditor wondered just how much disk space Windows RT takes up - in other words, if you buy the 32GB Surface RT tablet, how much space is left for your stuff? It turns out that while Windows 8 RT is considerably smaller than its Windows 7 x86 predecessor, it's still huge by mobile standards.
Permalink for comment 539278
To read all comments associated with this story, please click here.
RE[4]: Not quite true
by Brendan on Sat 20th Oct 2012 08:55 UTC in reply to "RE[3]: Not quite true"
Member since:


As far as I know, all magnetic storage manufacturers have always used "dodgy numbers" - a combination of binary and decimal. A "dodgy MB" is 1024*1000 bytes, which is slightly larger than a real MB and slightly smaller than a real MiB. A "dodgy GB" is 1024*1000*1000 bytes, a "dodgy TB" is 1024*1000*1000*1000 bytes, etc.

To add to the confusion, there's "unformatted capacity" (what the magnetic material is capable of), "low level formatted capacity" (what the magnetic material is capable of storing after it's been split up into sectors) and "formatted capacity" (how much free space you're left with after you've put the overhead of a file system on it).

For a simple example; a "1.44 MB" floppy disk has an unformatted capacity of about 2 MB, a "low level formatted" capacity of exactly 1440 KiB, and (depending on which file system you use) this probably drops to about 1300 KiB of free/usable space once a file system is slapped on it.

Of course everything else used for storage (RAM, file sizes, etc) is typically measured in binary sizes (e.g. 8 GiB of RAM); and there are still many morons that use decimal prefixes for binary sizes (e.g. 8 GB of RAM); so it's natural for people to assume a dodgy TB is a binary TiB and wonder why they've been ripped off. In this case the manufacturers like to pretend that file system overhead is the only cause, instead of admitting that their dodgy number scheme is a deliberate scam.

Now; the difference between "dodgy" and "decimal" is constant (e.g. a decimal MB is 2.4% smaller than a dodgy MB, and a decimal PB is 2.4 smaller than a dodgy PB). However, the difference between "dodgy" and "binary" increases with scale (e.g. a dodgy MB is 2.4% smaller than a binary MiB, and a dodgy PB is 9.95% smaller than a binary PiB).

This means that as hard drives get larger, the "dodgy sizes that people naturally assume are a binary sizes" scam grows. For example, by the time we get to yottabytes people will be getting 18% less disk space than they assume they're getting.

The simplest solution is to hunt down these morons that use decimal prefixes for binary sizes and "re-educate them with extreme force". Once people get used to binary sizes they'll start assuming that a dodgy MB is a real MB; and then people will get more disk space than they assumed they would from hard disk manufacturers.

TL;DR: The problem can be solved with violence! ;)

- Brendan

Reply Parent Score: 5