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.
Created attachment 355565 [details] MRG 1.1 patch
------- 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
Created attachment 358647 [details] scsi-fc-transport-removal-of-target-configurable.patch ported to MRG 1.2
------- 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. :)
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.
Renamed to be for MRG-1 kernels only. Made a clone for MRG-2 kernels (bug #520065)
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.
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 From sripathik.com 2009-10-09 11:36 EDT------- Saw the patch in 2.6.31.2-rt13.21.el5rt kernel.
------- 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