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Bug 514541

Summary: [FOCUS] [MRG-1] When the dev_loss_tmo fires don't remove devices by default.
Product: Red Hat Enterprise MRG Reporter: IBM Bug Proxy <bugproxy>
Component: realtime-kernelAssignee: John Kacur <jkacur>
Status: CLOSED ERRATA QA Contact: David Sommerseth <davids>
Severity: medium Docs Contact:
Priority: low    
Version: 1.1.2CC: bhu, jkacur, lgoncalv, ovasik
Target Milestone: 1.1.8   
Target Release: ---   
Hardware: x86_64   
OS: All   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 520065 (view as bug list) Environment:
Last Closed: 2009-09-01 07:39:22 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:
Bug Depends On:    
Bug Blocks: 520065    
Attachments:
Description Flags
MRG 1.1 patch
none
scsi-fc-transport-removal-of-target-configurable.patch ported to MRG 1.2
none
MRG1.2-rc6 patch none

Description IBM Bug Proxy 2009-07-29 15:22:01 UTC 
In R2 if you pull a Fibre Channel cable and the dev_loss_tmo expires
the fc transport class will remove the attached scsi devices (/dev/sdX
is deleted).  This behavior is altered in RHEL with the  BZ 215797 patch.

The problem with removing scsi devices is that the userspace 
(udev, multipathd) is not handling the hotplug events quick enough causing
various issues.

This defect is to port the patch published as part of Redhat BZ 215797 
and validate it.

Even with this patch, looks like we may still need to comment out the udev rule which invokes
/sbin/multipath on add path udev event.

This patch doesn't stop path add udev events delivering to the user-level udev device.
Hence the multipathd and multipath both are acting in un-synchronized fashion.

I think this patch can only avoid the need for modified multipathd (increased delay).
Testing is underway to verify that.

Looks like I drew conclusions little early. Looking at the dump and also the logs, looks like the
system is running fine..but very very slow in responding as the root and blast 
running on single path.

Patch is working fine..and the events generated by the patch are "change" events
not "new" events. Hence we can even remove the comment in the udev rules.

24 hour tests gave promising results. 

- I enabled the udev rule so that it goes back to default.
- I also replaced the multipathd to the one came with RHEL 5.2 installation.

Applied the ported patch, rebuilt the kernel, booted.
With this , blast runs fine, and port bounces are not causing any
disturbances in mpath paths.

This looks good and requesting to mirror this for RH inclusion.
Comment 1 IBM Bug Proxy 2009-07-29 15:22:05 UTC 
Created attachment 355565 [details]
MRG 1.1 patch
Comment 3 IBM Bug Proxy 2009-08-21 21:40:45 UTC 
------- Comment From jvrao.com 2009-08-21 17:37 EDT-------
Strange.. I don't see this patch on MRG 1.2 either...but I remember seeing this sometime back in one of the early releases of MRG 1.2...anyway. We need this patch
on MRG 1.2. Please absorb it.

Thanks,
JV
Comment 4 John Kacur 2009-08-25 22:51:47 UTC 
Created attachment 358647 [details]
scsi-fc-transport-removal-of-target-configurable.patch ported to MRG 1.2
Comment 5 IBM Bug Proxy 2009-08-26 02:00:43 UTC 
------- Comment From jvrao.com 2009-08-25 21:56 EDT-------
(In reply to comment #19)
> Created an attachment (id=47783) [details]
> scsi-fc-transport-removal-of-target-configurable.patch ported to MRG 1.2
>
>
> ------- Comment (attachment only) From jkacur 2009-08-25 18:51:47
> EDT-------
>

I have ported the patch to MRG 1.2 and compared with this...and it matches properly.
I have tested my patch successfully which implies this is also tested. :)
Comment 6 IBM Bug Proxy 2009-08-26 04:41:56 UTC 
Created attachment 358667 [details]
MRG1.2-rc6 patch


------- Comment on attachment From jvrao.com 2009-08-26 00:31 EDT-------


This is what I have done..and looks similar to what jkacur has done.
Comment 7 David Sommerseth 2009-08-28 08:48:38 UTC 
Renamed to be for MRG-1 kernels only.  Made a clone for MRG-2 kernels (bug #520065)
Comment 8 David Sommerseth 2009-08-28 09:12:20 UTC 
Verified by code review.  Found patch in comment #2 as mrg-rt.git commit 26d4c087a459be929f577829d68394cfad96eea2, implemented as bz514541-scsi-fc-transport-removal-of-target-configurable.patch in kernel-rt-2.6.24.7-132.src.rpm.
Comment 10 errata-xmlrpc 2009-09-01 07:39:22 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-2009-1239.html
Comment 11 IBM Bug Proxy 2009-10-09 15:40:54 UTC 
------- Comment From sripathik.com 2009-10-09 11:36 EDT-------
Saw the patch in 2.6.31.2-rt13.21.el5rt kernel.
Comment 12 IBM Bug Proxy 2010-07-27 15:11:34 UTC 
------- Comment From sglass.com 2010-07-27 11:06 EDT-------
Based on:

> Comment  #25 From SRIPATHI KODI  2009-10-09 11:36:03 EST  [reply] -------

> Saw the patch in 2.6.31.2-rt13.21.el5rt kernel.

Closing the bug