Bug 692859

Summary:	doc- Power_Management_Guide
Product:	Red Hat Enterprise Linux 6	Reporter:	Frederic Hornain <fhornain>
Component:	doc-Power_Management_Guide	Assignee:	Jack Reed <jreed>
Status:	CLOSED CURRENTRELEASE	QA Contact:	ecs-bugs
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.0	CC:	dayleparker, jskarvad, jskeoch, mhideo, pbokoc
Target Milestone:	rc	Keywords:	Documentation
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-06-22 00:14:54 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Frederic Hornain 2011-04-01 12:27:56 UTC

Description of problem:

In the documentation "Red Hat Enterprise Linux 6 Power Management Guide Managing power consumption on Red Hat Enterprise Linux 6" at chapter "Relatime Drive Access Optimization", it is written that we can modify the value of the 
using the relatime_interval= boot parameter - see below -

" Finally, to vary the default length of time before which the system will update a file's atime data, use the relatime_interval= boot parameter, specifying the period in seconds.The default value is 86400."

However, that kernel variable is apparently not available in RHEL 6 or F14.

Check with sysctl -A or look at /proc/sys/fs/relatime_interval.

The fs.relatime_interval does not exist. AFAIK, It existed in F-9. 

So except if I specify it in /boot/grub/grub.conf where could I change the default value of relatime_interval.

But I am not sure it is going to be taken in account.

So could you confim me that ?

Thanks in advance
BR
Frederic ;)

Comment 3 Jack Reed 2011-12-09 04:49:32 UTC

Hi Jaroslav,

Are you able to confirm whether the relatime_interval boot parameter is no longer in RHEL?

If not, how can the default value of relatime_interval be changed? Will editing the value in grub.conf be effective?

Thanks - Jack

Comment 4 Jaroslav Škarvada 2011-12-12 13:27:05 UTC

Hi,

AFAIK it is not settable since F10. Kernel upstream hard-coded 1 day. IIRC the consensus was that the usability of such tuning is low. I am unable to find the patch in the RHEL-6 VCS, thus probably the functionality was not there. I think we should update the doc.

Comment 5 Jack Reed 2011-12-13 02:10:51 UTC

Thanks, Jaroslav.

So is there no other way to adjust the time, ie: should I just remove the following sentence completely?

"Finally, to vary the default length of time before which the system will update a file's atime data, use the relatime_interval= boot parameter, specifying the period in seconds. The default value is 86400."

From: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Power_Management_Guide/Relatime.html

Or is there information I can replace it with?

Comment 6 Jaroslav Škarvada 2011-12-13 09:32:52 UTC

I would modify last two paragraphs, I propose the following (feel free to re-word):

The kernel used in Red Hat Enterprise Linux 6 supports another alternative — relatime. Relatime maintains atime data, but not for each time that a file is accessed. With this option enabled, atime data is written to the disk only if the file has been modified since the atime data was last updated (mtime), or if the file was last accessed more than a one day ago.

By default, all filesystems are now mounted with relatime enabled. You can suppress it for any particular file system by mounting that file system with the option norelatime.

Comment 9 Dayle Parker 2012-06-22 00:14:54 UTC

This bug is now fixed and available as part of the Red Hat Enterprise Linux 6.3 release on http://docs.redhat.com/.

Setting to CLOSED > CURRENTRELEASE.