
After less than 6 months of being a Mac user I was getting close to running out of space on my iMac 24″ with only 250GB drive and as I use my Mac more and more for pretty much everything it was just a matter of time before I would be in trouble.
Running out of space not only slows down your system over time but it also forces you to delete things you would otherwise hang onto if you had the extra space like old podcasts etc. (I am not suggesting that you don’t clean up your folders from time to time though).
So - I went out and got a My Book Pro Edition II 1TB. There are actually 2 physical drives inside the enclosure so I decided to mirror the two using the RAID application that was included - effectively giving me 465GB of space for all my media (for now at least)
I should not have to back that up as it is mirrored using RAID 1. (I will, however, make a monthly backup to my old Windows machine over the network once a month - just in case..)
After having plugged the My Book Pro Edition II into my Firewire 800 port on my iMac I daisy-chained my “old” My Book 500GB drive also using a Firewire 800 cable so I can access both drives with just one Firewire 800 connected to my iMac.
I then made a new Folder at the root level of the new mirrored drive which will serve as my new media location.
I started up iTunes and went to iTunes > Preferences > Advanced > General and changed the “iTunes Music folder location” to point to the new folder on the external My Book Pro Edition II drive. Then I went Advanced > Consolidate Library and the after accepting the warning that this can’t be undone my entire 135GB iTunes library was copied across to the new location.
Once everything was done - I checked a few files in iTunes (right-click > Get Info) to ensure the files where now at the new location - took a deep breath and dragged my local iTunes Music folder to the trash. You only want to delete the “iTunes Music” folder - not the other files or folders in the ~/Users/…/Music - in case your external drive is not connected then it will fall back on this directory.
So far everything is working quite well - obviously iTunes is not quite as responsive as it was when it was on my local drive - but it is not far off and certainly not a problem. The fan on the My Book Pro Edition II 1TB can be VERY noisy though (almost like a hairdryer) - but a firmware update fixes that.
Apple also have some details about moving iTunes that you might want to have a look at.