If LMDE breaks my system again, will I still be able to boot to Julia?
It seem your initial setup/upgrade issue with LMDE made you lose some confidence.
However, it might really help you to appreciate on the few issues on Debian based OS:
1. the good practice of using sudo apt-get update && sudo apt-get dist-upgrade
2. the 'need' to control your MBR.
and thus now you are trying to figure out what is 'best for you to move ahead'.
One more appreciation is the use of command line. Often it is nicer to use graphic interface. But one strenght on using terminal command is ( really) , it is easy to communicate over internet like what we are doing now, in addition to it being straight to the point of getting some work done.
I have been multi booting many OSes, and I used grub legacy as my Master Boot Loader ( the one controlling MBR), in the event I played with a new OS on a new partition, replace OS on existing partition, OS did some update & upgrade, I always paid attention to terminal and ensure I select boot code writing to root partition. This way I kept my MBR under controlled by the Master Boot Loader.
This is what would satisfy your question of "if LMDE break, at least you still can boot to Julia".
If you are keen to explore this method, I can help you in more details.
Three important things I used:a. Use grub legacy as my Master Boot Loader.
Some people used a dedicated partition. After some experiment for a while I ended up just use one OS that is fast and with some tools, then cater for one partition and let this OS control MBR with its default Grub legacy bootloader
Of course you can also convert Mint Julia grub2 to Grub legacy. However I tried not to do that because in the event when update/upgrade has kernel / grub change, like LMDE, it can take over and put back Grub2. So although it can be done, I avoided it for consistency on all my multi boot computers.
b. When installing any OS, I always instruct its own boot loader to install onto root partition.
This made thing consistent and when LMDE or other debian based OS ( such as Crunchbang, Aptosid, etc) go through the update/upgrade process, the terminal will show similar question on where I want to install boot loader, my selection is always root partition.c. Learn how to repair MBR and PBR.
This is quite easy to learn for me, after many experiments with several boot loaders.
For grub legacy, to repair MBR, just need to boot computer with Live CD, get into root terminal, tyoe grub and enter to have a grub prompt >, assuming I know my partition controlling MBR is at /dev/sda5, then the commands line are
that is it. After it ended, type quit to get out of Grub prompt> and back to terminal prompt #If I want to repair the PBR, then
that is it. then quit and get back from grub promt > to terminal prompt #