Description of problem: Quoting from DM Multipath Configuration and Administration: http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/DM_Multipath/queueifnopath_issues.html === 5.3. Issues with queue_if_no_path feature If features "1 queue_if_no_path" is specified in the /etc/multipath.conf file, then any process that issues I/O will hang until one or more paths are restored. To avoid this, set the no_path_retry N parameter in the /etc/multipath.conf file (where N is the number of times the system should retry a path). When you do, remove the features "1 queue_if_no_path" option from the /etc/multipath.conf as well. === It is not sufficient to add no_path_retry and remove the features "1 queue_if_no_path" option from /etc/multipath.conf to disable queue_if_no_path for SANs which have this option set as a default compiled into device-mapper-multipath. In this case it is also required to explicitly add features "0" to override this compiled in default. The documentation should be updated to reflect this. As of device-mapper-multipath-0.4.7-23.el5_3.4 the /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.defaults shows 10 SANs which use this compiled in default. Version-Release number of selected component (if applicable): DM Multipath Configuration and Administration Edition 3 Bugzilla component: Documentation-cluster Book identifier: DM_Multipath(EN)-5 (2009-01-06T15:35) Note this text is also incorrect in the release notes (in fact I think this text originally came from the release notes) http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Release_Notes/sect-Release_Notes-Known_Issues.html#id808732 Should another bug be opened on that as well?
I sent the following note to Ben Marzinski on August 7, since he is my main contact and reviewer for this project: Ben: Please look at Bug 513330 -- it indicates that some information in the multipath manual (which came from the release notes) is not complete. I don't know if we can update the release notes at this point, but if you can verify this I can get it into the manual next week. https://bugzilla.redhat.com/show_bug.cgi?id=513330 -Steven
The original comment is correct. If you would like to change the features parameter for a device that has a compiled in default configuration where the features option is set to "1 queue_if_no_path" You must add your override the compiled in devices section for your device with your own. This is usually done by copying the existing devices section for your device from /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.defaults into /etc/multipath.conf, and editting it to suit your needs.
Ben: How does this look, then, as a rewrite of the section in question: -------------------------- 5.3. Issues with queue_if_no_path feature If features "1 queue_if_no_path" is specified in the /etc/multipath.conf file, then any process that issues I/O will hang until one or more paths are restored. To avoid this, set the no_path_retry N parameter in the /etc/multipath.conf file (where N is the number of times the system should retry a path). When you set the no_path_retry parameter, remove the features "1 queue_if_no_path" option from the /etc/multipath.conf file as well. If, however, you are using a multipathed device for which the features "1 queue_if_no_path" option is set as a compiled-in default, as it is for many SAN devices, you must explicitly add features "0" to override this default. You can do this by copying the existing devices section for your device from /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.defaults into /etc/multipath.conf and editing it to suit your needs. If you need to use the features "1 queue_if_no_path" option and you experience the issue noted here, use the dmsetup command to edit the policy at runtime for a particular LUN (that is, for which all the paths are unavailable). For example, if you want to change the policy on the multipath device mpath2 from "queue_if_no_path" to "fail_if_no_path", execute the following command. dmsetup message mpath2 0 "fail_if_no_path" Note that you must specify the mpathn alias rather than the path.
Looks great.
With the release of RHEL 5.4, I am closing this bug.