iTunes, external hard drive and performance

In terms of your CPU it will make no difference at all. As for read / write times, modern Macs and most external HDs operate at 7200 rpm, and Firewire can handle data throughput higher than iTunes needs to play music.

The only unknown factor is, if you are using your Mac heavily for other apps too, how high or low down the "food chain" of OS X is the monitoring of Firewire ports, and whether you would notice anyway? I don't know the answer to that.

If you decide to move your iTunes, do read this article first:

http://www.ilounge.com/index.php/articles/comments/moving-your-itunes-library-to -a-new-hard-drive

Not really, as iTunes would still be using the CPU. The only thing you would save is on internal HD read times, which might be noticeable if you're using video editing software.

It also depends on what external HD you happen to be using - I used to use a LACIE drive connected via Firewire with hardly any noticeable difference - since buying this Macbook (no Firewire) I've "up"graded to a USB 2.0 Western Digital - and have had no end to problems with it "spinning" up and down as iTunes plays my music.

Basically once or twice every 60 seconds the music pauses for 1-2 seconds as the HD spins back up and start playing the music again. I've gone to almost exclusively listening to music on my iPod because of it. Spent a great deal of time at the WD forums to try and find an answer, nothing ever surfaced.

I would check to see if other users are using your particular external HD for iTunes playback for a more definitive answer - see if there are any documented problems such as mine (and hopefully it's not the same WD HD as mine!)

If you've got the room then it's time to experiemnt. Copy your entire iTunes folder to your external drive, then hold down shift when launching iTuens to get the option to create or choose a libray. Choose the one on the external drive and give it a test drive. If it works well then stick with it otherwise simply revert to the old library. Either way you now also have a complete backup for your library. I'm not a Mac user but I'm sure someone else could point you in the direction of a tool to keep the two folders up-to-date.

tt2

hold down shift when launching iTuens to get the option to create or choose a libray

It's actually the Option key on a Mac

Ah - consistency would be too easy 🙂

tt2

Since years, I use iTunes in combination with an external hard drive (firewire) because I have a fairly big library (200GByte) which would fill my internal hard drive unnecessarily. Contrary to USB, data transfers over firewire don't use the computer's CPU to operate (see http://en.wikipedia.org/wiki/Firewire#ComparisontoUSB). You will not have any problems concerning CPU power, iTunes will take its share either way (music on internal or external hard drive).

External firewire hard drives are MUCH faster (~40-80MByte/sec) than what is needed for a constant music stream (several Kbyte/sec for mp3, depending on encoding), don't worry about that, either. I also noticed that, even under heavy load, the music never stops, so iTunes always gets the CPU power needed to play. Mac OS X handles that very well, even when the CPU is under 100% load.



In conclusion, I would predict that you will not see any difference in performance, the resources used by iTunes are just the same in both cases. Also, iTunes in general is not very demanding, and will not make an noticeable impact on a computer's performance when using other programs at the same time. This is true for recent machines (Intel CPU), I am not sure about older computers, where you probably could feel the difference between iTunes on and iTunes off. I remember that I would get better frame rates in Unreal Tournament if iTunes was closed, but that was ~8-10 years ago. This would be independent of having your music on the internal or external hard drive, anyway.



The only question is: do you need your internal hard drive space or not? That, in my opinion, is the only criteria. As I need my internal space for other purposes, I have my iTunes library on an external hard drive.