i’m looking to buy an external hard drive but, when i look at the speck of all types n makes, they all state Mac or Windows operating systems. If i buy one, will it work on Linux Ubuntu? plus, i’m a deejay and want to buy some hardware with software from Native Instruments called “Traktor Kontrol S4” and they state the same with what OS it works with. SO, my question is, if they don’t work with Linux OS, is this gonna be a problem with a lot of soft/hard ware products/company’s???. thanks Billy.
Hardware isn’t normally an issue… ANY external hard drive should work with Linux, though some like the Maxtor Blackarmor drives include Windows security software that doesn’t work in Linux (and requires the drive to be formatted)… but even these will work, and you can use truecrypt if you need the security.
What the drive manufacturers probably mean is, the software that comes with the drive (backup software etc.) is only for Windows and Mac, but their are free alternatives in your package managers anyway.
If you’re unsure about a particular hard drive… post the make/model.
As for software… if you NEED specific “Windows” applications, and a Linux alternative won’t do… erm yes, you need Windows 
Linux alternatives (?)
Free and available in your package managers -
Mixxx have an active forum Mixxx - Mixxx DJ Software, it may be a good idea to ask/search on there for how well your Traktor hardware is supported.
and
http://djplay.sourceforge.net/
and
Screenshots – terminatorX
Free or commercial -
http://www.ultramixer.com/download.html
Hardware + Software
http://www.hercules.com/uk/ecafe/bdd/p/99/ecafe-trade-dj-kit-linux-/
There are probably more, that was only a quick search 
As I have commented in other threads be careful a lot of external drives have built in windows (sorry for swearing) security software that Linux will not work with.
Ah, but you’ve also proved it can usually be overcome … that said, I’d still steer clear of Blackarmor.
If it’s a software “security” solution that is included, that won’t be an issue… just wipe it.
But I think the Blackarmor drives also do something in hardware.
If you want to be 100% sure… either ask, or get a hard drive and an external hard drive enclosure, and build your own.
Yep, thats right.