Backup

[#1]

If using a dual boot system, linux and windows, is there any way linux can make a backup of the whole system ? ie linux and windows.

Having been caught out by making a back up of the windows partition only to discover a failing hard drive could only be read by linux . I do not want to be caught out again.

[#2]

Do you want a complete copy of the hdd if so look at Clonezilla
If only the data, mount the win drive while in Linux and copy the data somewhere else

[#3]

I periodically boot from a Linux USB and copy all files Partion-1 -> Partition-1 on backup device, Partion-2 -> Partition-2 on backup device etc. This way, I get a file level backup.

It is essential that you run your backup from a separate OS.

The massive initial copy will take ages, so you need to use rsync for future backups to get some speed!

Personally, I format the external disk with LVM, for flexibility.

[#4]

I use Acronis True image for backups.  That should allow you to back-up the entire hard drive.  You can do this from a boot disk but that's not necessary if you are running it under Windows.