Пакет psutil (https://pypi.python.org/pypi/psutil) имеет функцию disk_partitions.
Windows
>>> import psutil
>>> psutil.disk_partitions()
[sdiskpart(device='C:\\', mountpoint='C:\\', fstype='NTFS', opts='rw,fixed'), sdiskpart(device='D:\\', mountpoint='D:\\', fstype='NTFS', opts='rw,fixed'), sdiskpart(device='E:\\', mountpoint='E:\\', fstype='', opts='cdrom'), sdiskpart(device='F:\\', mountpoint='F:\\', fstype='NTFS', opts='rw,fixed')]
Linux:
>>> import psutil
>>> psutil.disk_partitions()
[sdiskpart(device='/dev/sda1', mountpoint='/', fstype='ext4', opts='rw,errors=remount-ro'), sdiskpart(device='/dev/sr0', mountpoint='/media/VBOXADDITIONS_4.3.10_93012', fstype='iso9660', opts='ro,nosuid,nodev,uid=1000,gid=1000,iocharset=utf8,mode=0400,dmode=0500,uhelper=udisks')]