iTunes and file format

The MAC can read but can't write to an NTFS drive.

On a PC you can format your drives as FAT32 or NTFS. The Mac can read and write FAT32 but can only read NTFS. The PC can't read or write a disc formatted in one of the Macs native formats. The best bet for you is therefore FAT32 since they both can read and write to the drive without special programs.

You need to have a backup drive anyway and they are very cheap now so buy another external drive and format it FAT32. Copy all of the files from the NTFS drive over to it. Once you are confident you have a good copy, format the NTFS drive as FAT32 and copy the files back to it. Now you have 2 drives with the same files that both computers can read and write.

I'm going to agree with Synthfreek on this one. If you change the iTunes music folder in advanced preferences to the new external drive then consolidate iTunes will copy everything over to the new drive AND use the files on that drive. If you simply copy as I suggested it will continue to play the files off of the original drive and once you reformat it you will need to delete the old iTunes library and add all of the files back into the new iTunes library. Easy enough to do but consolidating is easier.

This will not work

However, it should be pointed out that the drive letter assigned to a given external drive may be different depending on what computer it is connected to. In which case the iTunes program on each computer can easily be pointed to the iTunes folder on that drive by going to Edit/Preferences/Advanced within the iTunes program.

Changing this setting does not point iTunes to existing files. It only determines where iTunes will place any files added after that point. When you add a file to the library iTunes records the path to that file and looks for it in that location from then on. If you move the files and then change the iTunes folder to match the new location iTunes will still look where the files were, not where they are. Consolidating instead of copying changes the pointer and takes care of that problem,

Although alternatively the pointer in advanced preferences and the consolidate function could be changed/used twice, first to copy to the new drive and then to copy back.

Probably the easiest thing to do if you want to use the existing drive as the music drive and the new drive as the backup. That way you would be sure iTunes points to the correct drive.

That wouldn't work. You need to understand how iTunes finds songs. Take a look at the sample below of how iTunes stores the data about a song. Notice toward the bottom is the line that starts with Location file://localhost/Volumes/AIFF. The song "What's the Matter Here" is in a folder named "In My Tribe" which is a subfolder of "10,000 Maniacs" which is stored on the drive named AIFF. It stored it there because I had that drive selected as my music folder in advanced preferences when I ripped that song. When you click on the song in your iTunes library that is where it goes to get it, and if it isn't in that exact location it can't load it.

That location is stored when you first ripped or copied the song to the library. If you move it iTunes will still look where it was. If you change the storage location in advanced preferences that only changes where it will store things in the future.

Consolidating makes a copy of everything in the library no matter where it is stored and puts it all in the location listed in advanced preferences, and that changes the location stored in the database. If I changed my music folder in advanced preferences to D:\music\itunes and then consolidated it would take everything on my AIFF drive and copy it to the new folder and that line in the database would change to

D:/music/itunes/10,000%20ManiacsIn%20My%20Tribe01%20What's%20the%20Matter%20Here_.aif.

It would play it from the D: drive but the copy on AIFF would still be there.

You can also update the location stored in the database after moving when you select the song to play. iTunes will say it can't find it and you can browse to it to update the location. This is very tedious for a big library and it is easier just to erase the library and reload it, but you also loose things like play lists, ratings, and other metadata.

Track ID 9411
Name What's the Matter Here?
Artist 10,000 Maniacs
Album In My Tribe
Genre Rock
Kind AIFF audio file
Size 51483898
Total Time 291066
Track Number 1
Track Count 12
Year 1987
Date Modified 2009-10-01T01:13:41Z
Date Added 2009-11-29T02:10:31Z
Bit Rate 1411
Sample Rate 44100
Artwork Count 1
Persistent ID B52BDC3F3661B448
Track Type File
File Type 1095321158
Location file://localhost/Volumes/AIFF/10,000%20Maniacs/In%20My%20Tribe/01%20What's%20the%20Matter%20Here_.aif
File Folder Count -1
Library Folder Count -1