Hi there,

I am half noob and now testing the Debian 8.2 and installed on a win10 notebook with 800GB free space, I use the BIOS to switch between the two system that worked fine, I specially created a separate HOME partition so that I could replace with other distro at later time without erasing my own files. By default the installer created a small 10GB partition for the ROOT, and the rest as HOME, I don't know what governed this arrangement, but I worry 10GB may not be enough for user applications, or they will installed on the HOME instead ?

Applications generally go to /usr/local or /opt. You can either reinstall and allocate a bit more space or just resize home partition and use the free space to create another partition to use as /usr/local or similar.

Can I simply boot a live system to reduce HOME make room for ROOT ? installing pure Debian is not as simple as Ubuntu/Mint, I don't want to redo everything if possible.

Normally yes - let's see the output from these.

Sure. You don't even need a LiveCD. Just login as root and unmount /home. You can then resize it using something like:
https://www.howtoforge.com/linux_res...xt3_partitions

I suppose Gparted can do the same via live boot yeah ?

Correct.

It worth hours of wait to move and resize the partitions with Gparted, it finished without issue !

It is better to prepare a partition for data instead of sharing /home partition between different distros, because there are many files for configuration of many applications (packages) under /home/USER_NAME, which may interfere the correct operation under different distros with different version of the applications.
You can mount the partition for data by setting /etc/fstab or by udisks or so with a label of the partition.

I mean I may replace the distro and keep my own files without the need to backup first, I will only install one distro alongside win10

Yes, kiyop is saying there are configuration files in /home that can mess things up when you reinstall. If you install a different distro or change the install options of Debian when you replace your current installation, there's a good possibility of some (possibly minor) problems.

Oh I see, thanks !