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Hi all got a weird situation here. The other day I noticed when I wanted to seed a file for an older torrent, that the file size was wrong on my computer. The torrent said the file was say 450 mb, but when I went to look for the file, it was listed as say 480 mb! Bigger by maybe 10%.

This was just weird, but turned out to be a big pain in the butt because I made a vdi file for virtualbox at a fixed size of 15.8 gigs, and now it is listed as 17 gigs on Ubuntu! Which means I can't put it on the 16 gig memory stick I have!

(And yes, the memory stick has enough room for 15.8 gigs on it, in case anyone is wondering)

So, this is not the end of the world, I just have to buy a 32 gig stick now, but I am like WTF you know?? What gives as the kids say.

All other sources of information are consistent, and therefore Ubuntu is wrong. The website says the file is 450, the torrent file and the torrent client all say the file is 450. Virtualbox says the file is actually 15.8 gigs, it even handily provides an "actual size" value which says...15.8 gigs!

Only Ubuntu is giving these larger numbers. Therefore Ubuntu is wrong.

Why, dear goddess why??

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1 Answer 1

You need to be careful with dealing with file/disk sizes. Some systems/applications/advertisements use a base-10 measurement (so 1 K bytes is 1000 bytes) whereas others use a base-2 like system (so 1 K bytes is 1024 bytes) and some use a weird mixture ( 1 K is 1024 bytes but 1 M is 1024000).

See http://en.wikipedia.org/wiki/Mebibyte

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yeah I noticed a discussion about that. But it doesn't help me here. Ubuntu is apparently not using the same system as everyone else. –  RhZ Apr 11 '13 at 4:05
    
That is true. But this has been a problem for decades. I was once asked to set up a drive into 512MB partitions (circa 1994). I later learned the user was very frustrated because he could not completely backup the partitions onto his 512MB tapes. Part of the problem was they used different measurements.The other problem is that overhead of file system layout was not accounted for. [Think of 1.44MB Floppy Disk iff using MS-DOS, but 1.4MB iff using Mac, 2.0MB iff unformatted] Trying to size things for a perfect fit is very difficult. –  Scott Salley Apr 11 '13 at 4:24
    
Ok you are right, I thought about it and the increase is basically right. Frustrating for sure, and I could have sworn my work ubuntu, also 12.04, doesn't do this. I will check that soon, is it possible that two different installs would have different results? –  RhZ Apr 11 '13 at 5:03
    
First, here is a longer post on the subject: askubuntu.com/questions/465/… –  Scott Salley Apr 11 '13 at 5:48
    
Wow. So all ubuntu over a certain vintage...actually this might make sense, at work we have two comps with 10.04 and I think on those computers the number for that vdi file are "right". So 12.04 already does this but 10.04 perhaps does not. –  RhZ Apr 11 '13 at 6:15
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