questionswhat's taking up the extra room on my external?


One reason you may seem to have less than you expected is the problem with how "Gigabytes" are counted.

Sometimes, it's billions of bytes (where a Kbyte is 1000 bytes), sometimes it's the way we measure memory, where a Kbyte is 1024 bytes. 1024 x 1024 x 1024 is 1,073,741,824 bytes where 1000 x 1000 x 1000 is only 1,00,000,000,000 bytes.

That's a 73 Megabyte shortfall per gig. On a 500 gig drive, that's almost a 37 gig shortfall.

Other possibilities are filesystem overhead, hidden files, partitions that leave space on the drive, and so forth.


@rhmurphy: Sounds like it might be the counting issue. It's a 500gb external. I formatted it when I purchased it and then copied everything over, so there shouldn't be any hidden files or partitions, since it's just .mp3 and .ipa files.

The formatting is covered though, the capacity is 499.75 or something. Is there a way to fix the counting issue?


Could it be all the album art and ancillary stuff that itunes saves along with the music? That combined with the counting issue might account for the extra space.


@thedogma: One way to get the info uses the command prompt.
Start/run, type "cmd.exe" (no quotes) and hit enter.
At the "C:\Users....>" prompt, type the drive letter of your external drive, a colon, then press enter. (i.e. "E:{enter} " if the external drive is the E drive.

Now, type "dir /s/a" and let it chug along.
You'll see at the end:
Total Files Listed:
xxx File(s) 1,234,567,890 bytes
yyy Dir(s) 222,222,222,222 bytes free

So, now you've got it all in bytes. There's also overhead for the directories that isn't accounted for in the total above. Additionally, each file may have unused space at the end that's not counted here. Since the cluster size for your drive is 4096 bytes, you can adjust for that by adding 2048 times the number of files and directories to the total. (This is a guess, assuming on average half of the slack space is wasted.)

Personally, I don't worry about that level of detail. But you did ask. :)


@okham: I don't believe so. I think album art stays on the internal. I don't see it anywhere, anyhow haha.

@rhmurphy: I am on a Mac... but I'll investigate the same idea but for my OS. Thanks!


@thedogma: You could try this program:
I use an equivalent program on Windows called TreeSize and its awesome.


Try this tool:

It makes a pretty picture of your drives and shows you where big files are.


@thedogma: On a Mac, you can bring up a Terminal window and type "df -H" to display what the disk is using - look for the "/Volumes/{volumeName}" line.
The numbers displayed there are in Gs, where a gig is 1 billion bytes (100010001000).

Using "df -h" shows you in Gi's, where a gig is 2^30 bytes (102410241024).

You can use 'du' to display the usage as well - "du -s /Volumes/{volumeName}" will tell you how many bytes the files are using on that volume; then, to count the number of files, "ls -laR /Volumes/{volumeName} | wc -l"
Once you know the number of files, you can then account for the filesystem overhead (2048 * number of files) to see if it works out.


Oops. In the above, the formatter replaced asterisks.. what I meant to say was 1000 x 1000 x 1000 for Gb and 1024 x 1024 x 1024 for Gib.
See for a full story.


@rhmurphy: I missed that you were on a Mac. Instead of WinDirStat, try Disk Inventory X:


@rhmurphy: Would running Disk Utility help at all, do you think? It's fixed counting issues on the internal before


I highly recommend this free software to give you a graphical view of your drive. Sure when you run it it looks like PacMan is chewing through your drives reminiscent of the movie Hackers, but don't be afraid.

WinDirStat is a disk usage statistics viewer and cleanup tool for various versions of Microsoft Windows.

Edit: I now see someone posted this there. Vouch.