An interesting change in Mac OS X 10.6 is that Apple switched the representation of file and hard drive sizes to base-10 SI units instead of using binary prefixes. This means that a 60 GB hard drive which usually shows up as 55.8 GB will now appear within a few megabytes to the advertised 60 GB. I wasn’t really that happy with the idea at first, but when you think about it, it actually makes a lot of sense.
Bits and bytes
Now, it seems logical that since a computer works in binary, file sizes need to be represented with binary prefixes too. But in reality, the number of bytes in a kilobyte is completely arbitrary – since the operating system and the applications that run on it only represent file sizes in bytes. We could decide that there were 2504.25 bytes in a kilobyte and the computer wouldn’t care at all. If we’re just shortening the sizes for our convenience, why make it so hard for ourselves? Doesn’t it make more sense that a 1500KB file is 1.5MB, and not 1.464MB?
But what about file transfers?
I’ve heard people say that changing file sizes to SI units will make working file transfer speeds confusing, but the opposite is actually true – bitrates are actually already represented in SI units, so changing how files are represented on disk would make it easier to work out how long files would take to transfer.
Ram and SSDs
Now, since hard drives are designed around SI units, it makes sense to use SI units to represent its capacity and file size in SI units. But what about solid state drives and RAM? Well, RAM should stay as binary sizing, but as for solid state drives, it doesn’t really matter. The only difference is that a SSD sold as 256 GB (which is actually 256 GiB using the correct prefix) would show up as being 274.9 GB instead. Does this really matter? We’ve put up with our hard drives showing up as being smaller for so many years (a 1TB drive appears to be 92.677GB smaller), so I don’t think it’d be too bad.
Really, all we need is standardisation. A good first step to this would be to show RAM, solid state drives and hard drive sizes using the correct prefixes (GB and MB for SI units and GiB and MiB for binary). Unfortunately ‘mebibyte’ and ‘gibbibyte’ sound pretty stupid compared to megabyte and gigabyte though… But that’s all the more reason to switch to SI units.
