On a computer normally running Windows 7 (sda4) and Linux (Mint, sda5) in dual-boot, I have created two separate partitions (sda6 and sda7) within the same extended partition (sda3) as the Mint installation (sda5), in order to install other operating systems for test purposes , especially Linux, but also Windows 10 Technical Preview.
So, there are 5 main partitions, one for each operating system installed, and one separate ntfs partition (created with the initial Windows 7 installation). In Linux, the Gparted program shows the partitions like this:
So, Windows 10 (sda7) is inside the same extended partition (sda3) as Mint (sda5) and another Linux (Xubuntu-based Voyager on sda6), while Windows 7 on sda4 is outside the extended partition sda3.
In Mint (Thunar file manager) all drives are visible:
In Windows 7 (sda4), as expected, the ext4 drives of the Linux systems are not visible, but all ntfs drives are:
But in Windows 10 (sda7), one ntfs drive (sda2) is not accessible:
Why is that?
Is it because Windows 10 is inside an extended partition while the big ntfs drive (sda2) that is not accessible is outside that extended partition? But Windows 7 sda4 partition is also outside it and is still visible from Windows 10.
Could it be because sda2 is before the extended partition in which Windows 10 is installed? --- (sda2 is also before the Windows7 sda4 partition, from which it is still visible, but maybe what counts is also the difference that sda4 is not inside an extended partition...)
Windows 10 was the last system installed and that resulted in it being the only bootable system, so I had to repair (remove and reinstall) the grub from a Linux live usb.