jacklhoward wrote:
Excepting the efi partition the user can choose the number of additional partitions from a single one for the whole installation, or more.
It depends on what the problem is. /boot holds the kernels, initramfs files, grub and the efi partition and each can be repaired by different means with robust and reliable linux tools.
"/root" is actually the home directory for the root user, but I guess you mean the root partition. In addition to the previous answer, there are command line tools in a linux installation to carry out repairs, and GUIs for some of them, and there are live distros which can be written to cd, dvd or usb that can be used to make repairs, and also specialised rescue disks which may have additional advanced tools. As for mirrors, they are usually for downloading packages, but may also hold iso images which can be downloaded and written to disks or usbs that can be used for repairs.
There is a program to manage the efi partition (efibootmgr) and the grub bootloader has means of repair and rescue that are also robust and reliable. There are also alternative boot loaders for linux.
It's not difficult to agree with your last expression: "you shouldn't worry". No, you shouldn't.
It's worth making the point that the linux operating system is not MS. It's its own "thing" with a derivation from UNIX that long predates MS and a history deeply rooted in that derivation. Thus, it has its own learning curve, its own culture, its own fascination and phenomenal power, among many other benefits and advantages, not the least of which is the freedom to construct things in an infinite number of ways to satisfy your needs and wishes on your computer.