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Bug 524505

Summary: minimum RAM is too big and not explained well enough
Product: [Retired] Fedora Documentation Reporter: John Reiser <jreiser>
Component: release-notesAssignee: John J. McDonough <wb8rcr>
Status: CLOSED NEXTRELEASE QA Contact: Karsten Wade <kwade>
Severity: medium Docs Contact:
Priority: low    
Version: develCC: eric, kwade, solarflow99, vanmeeuwen+fedora, wb8rcr
Target Milestone: ---   
Target Release: ---   
Hardware: i686   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2009-10-27 14:53:57 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description John Reiser 2009-09-20 21:53:15 UTC 
Description of problem: Apparently the installer insists on at least 512MB RAM for graphical install from DVD on i686.  At least, anaconda refuses 383MB and falls back to text mode.  [Text mode install lacks many features and requires much higher user knowledge to achieve success.]

In contrast, the Wiki says that 256MB is the recommended minimum RAM for graphical operation on Fedora *12*:  http://fedoraproject.org/wiki/Docs/Beats/HardwareOverview#Processor_and_memory_requirements_for_x86_Architectures

I ran a (self-composed) DVD install of yesterday's rawhide on a 4GB machine, and at the end of install the memory usage of the large processes totalled only 225MB:
 F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
 4     0   294    85  20   0 192748 145012 poll_s S+  tty1       8:46 /usr/bin/python /usr/bin/anaconda --stage2 cdrom:///dev/sr0:/mnt/stage2 --graphical -
 4     0   348   294  20   0  31968 12532 poll_s Ss+  tty6       0:34 Xorg -br -logfile /tmp/X.log :1 vt6 -s 1440 -ac -nolisten tcp -dpi 96

Therefore it is hard to understand anaconda's refusal to install with 384MB, and even harder to comprehend a 512MB minimum requirment for RAM.

Why is the requirement so big?  What are the two leading factors which prevent success with less RAM, and how low would the requirement be if those factors were ameliorated?

Version-Release number of selected component (if applicable):
anaconda-12.26

How reproducible: always


Steps to Reproduce:
1. Attempt DVD install on i686 with 384MB RAM (383MB available)
2. Perform DVD install on i686 with 4GB RAM; at finish, switch to VT2 and ask "ps axl"
3.
  
Actual results: 384MB: "You do not have enough RAM for graphical install.  Falling back to text mode."

4GB: success with main python anaconda process using only 193MB, X server using only 32MB.


Expected results: Successful graphical install in same memory as suggested minimum RAM for graphics (currently 256MB on i686; and there is no problem in daily operation with only 384MB RAM.  [It's not zippy, but it's quite usable, particularly after prelink has run once.])


Additional info:
Comment 1 Chris Lumens 2009-09-21 14:10:19 UTC 
You can't simply use the same requirements as the running system for anaconda, though, because anaconda has additional restrictions for the environment it must run under.  For starters, anaconda has the whole stage2 environment stored in memory.  There's simply nowhere else for it to go.  That adds well over 100 MB to the requirements.  You'd only be able to decrease the memory requirements if you were able to decrease the size of the stage2 image, and software doesn't seem to be getting smaller over time.

If the memory requirements are not well enough explained, that sounds like a problem in the installation guide.
Comment 2 John Reiser 2009-09-21 15:15:35 UTC 
(In reply to comment #1)
> For starters, anaconda has the whole stage2 environment stored
> in memory.  There's simply nowhere else for it to go.  That adds well over 100
> MB to the requirements.

It seems to me that stage2 could be [effectively] stored in different places during different stages of install.  For example, what about putting stage2 into a RAM-resident filesystem that can be paged to disk (such as tmpfs?)  Then most of the requirement for 130MB RAM for stage2 "disappears" as soon as there is paging space ("swap space.")  Swap space appears before package install, which is the big consumer of RAM.

In Fedora 9 and 10 the anaconda python process itself grew to many hundreds of megabytes, which became an effective limit due to page thrashing on machines with small RAM.  Now the anaconda python process behaves better (see data in Description.)
Comment 3 David Nalley 2009-10-19 01:25:04 UTC 
The install guide - at least for the past couple of iterations referred the 'minimum memory' issue to the Release Notes, and the IG has nothing other than a pointer there. Indeed the link you reference above is a beat location for the Release Notes, so I'm changing the componet to RN. 

Thanks
Comment 4 John J. McDonough 2009-10-27 14:53:57 UTC 
529401 includes a detailed discussion of why the minimums are too SMALL.

Notes includes an admonition with some weasel words.
Comment 5 John J. McDonough 2009-10-27 14:57:12 UTC 
*** Bug 516629 has been marked as a duplicate of this bug. ***