installation-guide: simplify RAM/disk space requirements

[Holger Wansing <hwansing@mailbox.org>]

Hi all,

as a follow-up to #1032940, I think we have some open points in the doc regarding
RAM/disk space requirements.

In the installation-guide, we have 3 places referring to needed RAM/disk space
size, and unfortunately they are not very well conform with each other:
(at least for the end-user POV, who does not know all the details and tricks)


chapter 2:
https://d-i.debian.org/doc/installation-guide/en.amd64/ch02s05.html
says
"You must have at least 780MB of memory and 1160MB of hard disk space to 
perform a normal installation."



chapter 3:
https://d-i.debian.org/doc/installation-guide/en.amd64/ch03s04.html
says
"Table 3.2. Recommended Minimum System Requirements

Install Type	RAM (minimum)	RAM (recommended)	Hard Drive
No desktop	256 megabytes	512 megabytes	4 gigabytes
With Desktop	1 gigabytes	2 gigabytes	10 gigabytes	"



And chapter D.2:
https://d-i.debian.org/doc/installation-guide/en.amd64/apds02.html
has a table for different tasks:

"Task	Installed size (MB)	Download size (MB)	Space needed to install (MB)
Desktop environment	 	 	 
  • GNOME (default)	3216	859	4075
  • KDE Plasma	4584	1316	5900
  • Xfce	2509	683	3192
  • LXDE	2539	693	3232
  • MATE	2851	762	3613
  • Cinnamon	4676	1324	6000
Web server	85	19	104
SSH server	2	1	3	"





I remember some reports from users in the past, saying that the values in
chapter 2 are totally unrealistic, and the answer from debian-boot was
"Well, those values are minimal values over all archs", so a light-weight
arch could work with those values indeed. But for most users those values
are not real-world.
But hey, for those people, there is the link to chapter 3:
"Note that these are fairly minimal numbers. For more realistic figures, 
see Section 3.4, “Meeting Minimum Hardware Requirements”.
So, if chapter 2 advise is of no value at all, why not skip it completely?
Or make it compliant with chapter 3. ???



I would like to get this into a better shape, so that the different chapters
are talking "with the same speach" (and don't conflict).


To get this done, I propose to change (or unify) the values in chapter 2 + 3, so 
that they show a consistent picture.


I did some test installations with QEMU on amd64.
The results are:	Installing with 256 MB of RAM fails, the installer 
			stopps with "320 MB RAM is required"

			Installing with 512 MB of RAM switches to low-memory
			mode installer, but the installation succeeds.


So I propose to change chapter 3 values like

  Install Type	RAM (minimum)	RAM (recommended)	Hard Drive
- No desktop	256 megabytes	512 megabytes	4 gigabytes
+ No desktop	512 megabytes	1 gigabytes	4 gigabytes
  With Desktop	1 gigabytes	2 gigabytes	10 gigabytes




So:

1.
To have chapter 2 compliant with chapter 3 (regarding RAM size)

and
2.
since we have changed the minimal harddisk value to 4 gigabytes in 
bug#1032940 (harddisk size)

and
3.
since users will probably misinterpret the phrase of "a normal installation" here
(What is a *normal* installation? What is *normal* in this case? I would skip 
the *normal* here and just talk of *an installation*. )

I would propose to change chapter 2
like

- You must have at least 780MB of memory and 1160MB of hard disk space to 
- perform a normal installation."
+ You must have at least 512MB of memory and 4GB of hard disk space to 
+ perform an installation."




Comments?

Holger



-- 
Holger Wansing <hwansing@mailbox.org>
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