Bug 712339

Summary:	Kernel 2.6.18-238.12.1.el5 ext4 barrier bug
Product:	Red Hat Enterprise Linux 5	Reporter:	Darren <darren.eckhoff>
Component:	kernel	Assignee:	Red Hat Kernel Manager <kernel-mgr>
Status:	CLOSED NOTABUG	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	5.5	CC:	rwheeler
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-06-10 14:52:24 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 Darren 2011-06-10 10:46:29 UTC

Description of problem: 

After patching one of my servers that uses ext4 filesystems with the newest kernel (2.6.18-238.12.1.el5) I began getting the following messages in the syslog:

kernel: JBD: barrier-based sync failed on <disk> - disabling barriers

I rebooted using the previous kernel and the messages did not appear again.

This is occurring on my SAN disks using multipath devices.  I don't know if it is isolated to them or not.


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

RHEL 5.5, kernel 2.6.18-238.12.1.el5

How reproducible:

Happens every time during boot up.

Steps to Reproduce:
1. Install kernel 2.6.18-238.12.1.el5 on system with ext4 filesystems using multipath devices
2. Reboot
3.
  
Actual results:


Expected results:


Additional info:

Comment 1 Darren 2011-06-10 10:56:37 UTC

Correction: This is not SAN storage or multipath devices.  It is local (single path) disk devices.

Comment 2 Ric Wheeler 2011-06-10 11:18:02 UTC

This is an expected (informational) message when the storage does not support barriers.  It should work on local storage (S-ATA and SAS drives), can you run "hdparm -I /dev/sda" and add that in.

Please open a support ticket through RH officially. RH bugzilla is not meant to be a customer facing support tool since that cuts our field support out of the loop.

Thanks!

Comment 3 Darren 2011-06-10 14:42:32 UTC

After doing some further researching I discovered the devices it is complaining about aren't disk devices that the system is using at all because checking /proc/mounts shows that all EXT4 filesystems have barriers enabled (barrier=1).  So the new kernel is checking for barrier support on devices that the previous kernel was not.  The devices reported were in the format dm-#-#, such as dm-0-8.  I'm assuming this is some type of dm-multipath device but it doesn't refer to any of my disk devices.

Anyway, it isn't affecting us so feel free to close this ticket.

Thanks.

Comment 4 Ric Wheeler 2011-06-10 14:52:24 UTC

Thanks Darren - in RHEL6, barriers will work for dm and lvm smoothly as well.