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Bug 463470

Summary:	Regression: multipath was setting the REQ_FAILFAST flags which caused a performance drop
Product:	Red Hat Enterprise Linux 5	Reporter:	Mike Christie <mchristi>
Component:	kernel	Assignee:	Mike Christie <mchristi>
Status:	CLOSED ERRATA	QA Contact:	Martin Jenner <mjenner>
Severity:	high	Docs Contact:
Priority:	high
Version:	5.3	CC:	bmarson, coughlan, mgahagan
Target Milestone:	beta	Keywords:	TestBlocker
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2009-01-20 20:00:58 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 Mike Christie 2008-09-23 16:14:29 UTC

Description of problem:

multipath and dm-multipath were setting the REQ_FAILFAST flag instead of the BIO_RW_FAILFAST. REQ_FAILFAST maps to a barrier request, so this results in multipath/dm-mulitpath IO being a lot slower.


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


How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:

Comment 1 RHEL Program Management 2008-09-23 16:45:07 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Comment 4 Don Zickus 2008-09-30 16:02:00 UTC

in kernel-2.6.18-117.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Comment 7 errata-xmlrpc 2009-01-20 20:00:58 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2009-0225.html