I've been told by my ISP I'm using too much bandwidth so after using Activity Monitor to see that I'm using ~2GB a day I've used the nettop command line utility to work out where. Turns out it's iTunes.

I don't use it for downloading/streaming music (other than podcasts of which I definitely don't have 2GB of new ones a day) or movies. What is iTunes doing?

This is on a late 2009 MacBook running Lion 10.7.5 with iTunes version 10.7

UPDATE: Genius (and store and home sharing) all disabled (today to try and track this down) and data still being gobbled - these things are pushing data out anyway right, I'm not using match, files are all local, not buying anything. Seems to be an intermittent thing, data being static while I'm looking but will have jumped by xMB next time I check.


Turns out it was podcasts after all. One of the downloads had become stuck somehow, so it would repeatedly download it and then throw it away. Looks like iTunes has some flag other than the podcast update frequency for when to download episodes in it's "download this one db" as I had it set to check once a day but this was happening much more frequently.

Hope this helps someone else at some point as this drove me crazy!


cjb110's answer is pretty good, just adding on here. Genius and iTunes Match uses data, along with any iCloud services. If you are purchasing new apps/music/podcasts/movies on your other devices, iTunes will automatically download them to itself. This could be cause. And yes, iTunes does not copy files to it's own directory, therefore if you have the music files on another computer and are are accessing them from your MacBook, then iTunes has to constantly stream the information over.

Check those things and if you still have a problem, let me know.

  • not buying anything either – George Oct 11 '12 at 16:02
  • You don't really need to be buying anything. If you already have a lot of apps, then you will be seeing a significant number of updates as new versions are released to support iOS6/IPhone 5. – sgmoore Oct 11 '12 at 16:46
  • no ios devices either, sorry – George Oct 11 '12 at 17:27
  • That's odd. Have you checked the Apple Support Fourms? – Josiah Oct 11 '12 at 21:14

Depending on your skill/comfort level, you could try using a network analyzer like Wireshark to inspect what is going across the wire, this might yield some additional clues.

  • I think Wireshark probably would have done it, assuming it would show you the source of the incoming traffic (never used it) though I discovered the culprit before having to resort to it. – George Oct 12 '12 at 8:25

Genius sends/receives data, as will iTunes Match.

Try turning both of them off.

Also just checking, your iTunes library and data files are all on your MacBook and not on another PC/Server somewhere?

  • nope, all local, not using match, genius disabled – George Oct 11 '12 at 16:01

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