With Snow Leopard, Finder started reporting file sizes in base-10 rather than base-2. This means that when 10.6 users install a 500 GB hard drive, Finder will report that there are 500 GB available on the drive. The practical aspect of this is that everyting is bigger by an order of 24K per 1000. Hard drives are bigger but so are the files that they hold.

This wouldn’t really even be noticeable if 1) this were not the age of the Internet and 2) if every other utility in 10.6 did not continue to use base-2 file sizes. /usr/bin/du reports base-2 file sizes. When Apache gets a directory listing and serves it up to an http client, it reports base-2 file sizes.

I’ve been especially vexed by these discrepancies during a recent filing project which involved tens of millions of files totalling in the low terabyte range. I’d occasionlly run to Finder for a quick heads up on size totals only to receive a completely different total when using /user/bin/du.

Apple should reconcile these discrepancies. Not only do they complicate and disrupt workflow, but in some cases they lead web developers to report erroneous information.1 2