I'm quite new to the world of Mac and OSX so sorry if this is a noob question.
I have a iMac but also still use a Windows PC and laptop running Win7. Before I had the Mac I used to use a small app called Sync Toy to sync files between my PC, external HDD and laptop.
Every month or so I would sync my entire iTunes folder on the PC to the HDD then sync the newly updated iTunes folder on the HDD to my laptop. This served as backup but also allowed me to have a exact replica of my iTunes on both the Mac and PC, down to playlists etc.
I now want to continue doing this but with the iMac in the mix. I'm looking for a app which would allow me to sync the Mac's iTunes folder to my external HDD because I'm using the Mac as my main machine now. If I can keep the external HDD in the format it is currently, I can still continue using Sync Toy on the Windows side to get the iTunes folder synced on to the PC and laptop. Syncing is esential, recoppying the entire folder from 1 HDD to another would take up a lot of time, my iTunes library is over 100 GB, plus it won't be very good for the hard drives to keep deleting and rewriting huge folders on a regular bases.
The easyest and most obvious way to do this which everyone all over the internet recommend is via the cloud, Dropbox, Google drive etc, but I currently don't have that much space in the cloud, as mentioned my iTunes library is over 100 GB.
Does anyone have a solution or recommendations?