Prerequisites: HDD System vs RAM

I tried installing OMV5 using the ISO in a VM with 3GB ram and 4GB system, but it failed with an out of space error.

According a reading of the prerequisites here: https://openmediavault.readthe…en/5.x/prerequisites.html I thought that I should be okay since 4GB was more than 3GB:

Prerequisites
Before installing openmediavault make sure your hardware is supported.

CPU: Any x86-64 or ARM compatible processor
RAM: 1 GiB capacity
HDD:
System Drive: min. 4 GiB capacity (but more than the capacity of the RAM)
Data Drive: capacity according to your needs

Another reading suggests that you need 4GB on top of what you have for RAM, so in my case 7GB. But then that doesn't seem to make sense as then the minimum HDD requirement would be 5GB. Indeed I manage to install with a 3+6 configuration.

Nevertheless I managed to progress through the install with 1+4. I suspect the installer is using the ram amount to create the swap partition. So my questions then:

1. Does the actual required HDD depend on the RAM? If so, how?
2. Assigning a 6GB HDD just because I want to provide more RAM seems a little overkill. Is there a way to configure the swap manually?
3. I imagine doing a 1+4 install and then bumping up the RAM will work. What's the downside to this? Why is the swap dynamically sized anyway?
4. Do I even need 3GB RAM? I was running 3+3 with OMV4 (I recall installing that with the ISO too) and only really use the NAS for file serving with a regular backup running regularly too.

I accept that this is a minor issue so I am mainly asking for academic reasons to increase my knowledge about how LInux servers can be configured.

To add/answer my own question, it appears that the OMV install:

• sets the swap = RAM
• takes 512MB for the boot (EFI in my case)
• leaves the rest for the system

A clean install uses around 1.6GB, a HDD of RAM + 3GB seems about right.

I would still appreciate thoughts on questions 3 and 4 above. For now I'll settle on 2+5.

I've gone with 1.5GB + 8GB.

Many thanks.