GRUB errors and proper guide to install dual systems

Question

I tried to install Ubuntu 19.10 the other day side by side with an existing Windows 10 on my DELL XPS 8900. In order to avoid erasing everything I used a tool called EaseUS Partition master.

I allocated half of 500G of my Samsung EVO SSD for Ubuntu; created a bootable CD and proceed to install it.

It showed the installation succeeded. However when I restarted the computer and chose Ubuntu from the menu it showed something like:

Minimal BASH like line editing is supported. For the first word, TAB lists possible command completions. anywhere else TAB lists possible device or file completions.

and it failed to start anything.

I tried reisntalling it three times to no avail.

I guessed I messed up when choosing boot, root or swap directories or file system types when installing Ubuntu.

Now I decided to buy and use a total physically separate SSD disk for Ubuntu, since I became a little rusty in installing Linux, I have a few questions that I appreciate any suggestions:

• What is the above GRUB error telling us? and what is the root cause for it?
• There are ext2, 3, 4 or other file formats for Linux, which one is to choose from and why?
• what and how to decide directory /, /root and /boot?
• How to allocate swap in term of size-wise?
• anything else in particular that I need to know to install Ubuntu in separate disk w/o interfering the other system? any proper guide?

any help is appreciated

Answer 1

What is the above GRUB error telling us? and what is the root cause for it?

Not much unfortunately. It tells that GRUB wasn't able to boot Linux. We can't tell more than that without further details.

There are ext2, 3, 4 or other file formats for Linux, which one is to choose from and why?

Go with ext4. It's the most modern one, most reliable and backwards-compatible. It's more resilient against data loss and fragmentation.

You could use ext2 for a read-only "filesystem device" or an embedded device where storage and performance is too limited to keep an ext4 driver in kernel. ext3 doesn't have many uses nowadays, it was a good improvement over ext2 but ext4 is better in every way if ext3 makes more sense than ext2 in your application (ie. almost always).

what and how to decide directory /, /root and /boot?

Use your preferred partition for /.

You don't need a separate /boot, it can live inside / just as well. An exception would be a situation where you want to fully encrypt / without LVM, in that case having /boot on a separate unencrypted partition makes the setup easier and more convenient. It's an unconventional setup though and if you choose to install with encryption, Ubuntu will implicitly use LVM, so this doesn't apply.

I can't see why you would need a separate /root.

How to allocate swap in term of size-wise?

Don't. Ubuntu 18.04 and later automatically create a file-based swap on /.

anything else in particular that I need to know to install Ubuntu in separate disk w/o interfering the other system? any proper guide?

It should Just Work™. Ubuntu uses pretty sane defaults. Don't complicate stuff too much and it will be smooth sailing.