Bug 481227
Summary: | multipath.conf: polling_interval is misleading in the docs | ||||||
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Product: | Red Hat Enterprise Linux 5 | Reporter: | Shane Bradley <sbradley> | ||||
Component: | device-mapper-multipath | Assignee: | Ben Marzinski <bmarzins> | ||||
Status: | CLOSED ERRATA | QA Contact: | Cluster QE <mspqa-list> | ||||
Severity: | medium | Docs Contact: | |||||
Priority: | low | ||||||
Version: | 5.3 | CC: | agk, bmarzins, bmr, christophe.varoqui, cward, dwysocha, edamato, egoggin, heinzm, junichi.nomura, kueda, lmb, mbroz, prockai, sghosh, tao, tranlan | ||||
Target Milestone: | rc | Keywords: | Documentation, FutureFeature | ||||
Target Release: | --- | ||||||
Hardware: | All | ||||||
OS: | Linux | ||||||
Whiteboard: | |||||||
Fixed In Version: | Doc Type: | Enhancement | |||||
Doc Text: | Story Points: | --- | |||||
Clone Of: | Environment: | ||||||
Last Closed: | 2009-09-02 11:48:15 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: | |||||||
Attachments: |
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Description
Shane Bradley
2009-01-22 21:27:07 UTC
Thread with patch attached: https://www.redhat.com/archives/dm-devel/2009-January/msg00197.html Created attachment 330376 [details]
patch to update docs on polling_interval
I can see how the original wording could confuse a person, however the wording in you attachment is not correct. multipathd doesn't always check all the paths every polling interval. A path is checked every polling_interval seconds after it was added. If paths were added at different times, they may not be checked at the same time. Also, If a path is usable, the time between path checks will gradually increase to (4 * polling_interval). This is because it is much more important to recover a failed path, than it is to preemptively fail an active path. If any IO attempts to use a path that is broken, but marked active, the kernel will automatically switch the path to a failed state. However the kernel is not able to try a failed path until multipathd has marked it as active again (well, that is not completely true, but it's close enough). This change in actual time between checks is yet another reason why different paths won't always be checked at the same time. Here is the change I made. Let me know if you think it is still problematic Index: multipath-tools-rhel5_4/multipath.conf.annotated =================================================================== --- multipath-tools-rhel5_4.orig/multipath.conf.annotated +++ multipath-tools-rhel5_4/multipath.conf.annotated @@ -28,7 +28,9 @@ # # # # name : polling_interval # # scope : multipathd -# # desc : interval between two path checks in seconds +# # desc : How often a path's state is checked, in seconds. For +# # paths that are usable, the time between checks will +# # gradually increase to (4 * polling_interval). # # default : 5 # # # polling_interval 10 ~~ Attention - RHEL 5.4 Beta Released! ~~ RHEL 5.4 Beta has been released! There should be a fix present in the Beta release that addresses this particular request. Please test and report back results here, at your earliest convenience. RHEL 5.4 General Availability release is just around the corner! If you encounter any issues while testing Beta, please describe the issues you have encountered and set the bug into NEED_INFO. If you encounter new issues, please clone this bug to open a new issue and request it be reviewed for inclusion in RHEL 5.4 or a later update, if it is not of urgent severity. Please do not flip the bug status to VERIFIED. Only post your verification results, and if available, update Verified field with the appropriate value. Questions can be posted to this bug or your customer or partner representative. 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/RHEA-2009-1377.html |