Bug 718235

Summary:	Recommended swap space is not clear
Product:	Red Hat Enterprise Linux 6	Reporter:	Robert Tidwell <rtidwell>
Component:	doc-Installation_Guide	Assignee:	Jack Reed <jreed>
Status:	CLOSED CURRENTRELEASE	QA Contact:	ecs-bugs
Severity:	high	Docs Contact:
Priority:	medium
Version:	6.0	CC:	bugzilla-redhat, jreed, jskeoch, pbokoc, rdassen, rprice, wnefal+redhatbugzilla
Target Milestone:	rc	Keywords:	Documentation
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-12-09 02:23:08 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Deadline:	2011-09-02

Description Robert Tidwell 2011-07-01 14:25:20 UTC

Description of problem:
Page 375 of the "Red Hat Enterprise Linux 6 Installation Guide" shows recommended swap space values that contradict what is described on page 96 and what is shown in Table 9.2.  Which one is supposed to be correct?

p.96: In years past, the recommended amount of swap space increased linearly with the amount of RAM in the system. But because the amount of memory in modern systems has increased into the hundreds of gigabytes, it is now recognized that the amount of swap space that a system needs is a function of the memory workload running on that system. However, given that swap space is usually designated at install time, and that it can be difficult to determine beforehand the memory workload of a system, we recommend determining system swap using the following table. 

Table 9.2. Recommended System Swap Space 
Amount of RAM in the System Recommended Amount of Swap Space 
4GB of RAM or less a minimum of 2GB of swap space 
4GB to 16GB of RAM a minimum of 4GB of swap space 
16GB to 64GB of RAM a minimum of 8GB of swap space 
64GB to 256GB of RAM a minimum of 16GB of swap space 
256GB to 512GB of RAM a minimum of 32GB of swap space 


p.375: To determine the size of the swap partition automatically, use the --recommended option: 
swap --recommended 
The recommended maximum swap size for machines with less than 2GB of RAM is twice the amount of RAM. For machines with 2GB or more, this recommendation changes to 2GB plus the amount of RAM. 

Version-Release number of selected component (if applicable):
6.0

Comment 2 Ruediger Landmann 2011-08-14 19:42:01 UTC

*** Bug 727568 has been marked as a duplicate of this bug. ***

Comment 5 Jens Kuehnel 2011-09-07 13:06:16 UTC

Hi,

I think the values in the table 9.2 is much more sane and better suited for machines with huge amount of mem than the defaults in anaconda.

If you have a machine with 96GB ram and you don't use oracle, but something like virtualization 98GB of Swap is not help full.
16GB of Swap is much better suited for "normal" usage.

I think this should be an anaconda bug and not a doc bug, code for that can be found in Bug 727568.

Page 96 is correct and Page 375 and anaconda is wrong.

Greeting
Jens Kühnel

Comment 6 Jack Reed 2011-09-14 04:55:26 UTC

Hi Jens,

Thanks for your feedback.

The documentation changes made in response to this bug now accurately reflect the swap space errors raised in the original report.

However, if you would like to address these values as they now stand, please feel free to open a new bug against Anaconda itself.

If changes are made as a result of this, we will ensure that the documentation reflects them.

Thanks again,

Jack

Comment 7 Jens Kuehnel 2011-09-16 10:27:00 UTC

Hi Jack,

I did that, see Bug 727568. But I was closed as duplicated.

CU
Jens

Comment 8 Jens Kuehnel 2011-09-18 11:40:41 UTC

Hi,

I still think it is a error to change the documentation that is correct instead of changing the code that is wrong. How wrong? There is even a KB 15252 which tells you exactly as I feel. Please accept that sometime code is wrong and docs are right.
Please don't break the sane docs, instead of fixing the code.

Greetings
Jens Kühnel