Bug 155546
Summary: | multipath-tools could benefit from more cmdline options | ||
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Product: | [Fedora] Fedora | Reporter: | Lars Marowsky-Bree <lmb> |
Component: | device-mapper-multipath | Assignee: | Ben Marzinski <bmarzins> |
Status: | CLOSED CURRENTRELEASE | QA Contact: | |
Severity: | medium | Docs Contact: | |
Priority: | medium | ||
Version: | rawhide | CC: | agk, christophe.varoqui, dmo, dwysocha, lmb, mbroz, poelstra, terescik_john, tranlan |
Target Milestone: | --- | Keywords: | FutureFeature |
Target Release: | --- | ||
Hardware: | All | ||
OS: | Linux | ||
Whiteboard: | |||
Fixed In Version: | Doc Type: | Enhancement | |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | 2011-02-14 21:42:36 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
Lars Marowsky-Bree
2005-04-21 11:25:17 UTC
I don't really follow you on this : the current design forces the admin to setup a config file suited to its env, then forget about it. Why would it want to care about direct map manipulations, that multipathd will reverse at the first occasion. As an example, force a fail_path on a valid path and you'll see it instantly reinstateed. Force a switch_pg to a pg with a lower weight, and you'll see a switch back to the highest prio pg. I think this is sane. Not to say an admin is not allowed to reap off the daemon to mess with maps, but it this case I don't see why multipath-tools would have to give assistance ... dmsetup is the right tool for that. I disagree partially. Ok, failing the paths might not be the best example, but switching PGs (or temporarily disabling one) does have it's merits. Use case 1: The admin wants to temporarily move load from one overloaded switch to another one. Of course, if that one fails, it should switchback to the other, because slow service is better than none - so disabling the switch ports isn't a good idea. Use case 2: Consider 2 nodes; one of them loses access to parts of the fabric and switches over. The other node constantly switches back. The ping-pong effect is going to cause problems. Of course, the real fix is to fix the first node, but the immediate workaround is to tell the second node to switch PGs. The option to set/disable the queue path option for testing is also useful. Sure, these are non-persistent and will be reset the next time the daemon is restarted and reloads its configuration file; that's just fine; having a volatile and non-volatile configuration is pretty standard. To summarize my position: I agree that the goal is to have the admin setup the configfile once, or even better, not require any configuration at all but just do the right thing out of the box. This is a great goal for user-friendliness and indeed very sane. However, almost every piece of logic should have an easily accessible admin override to cater to situations where the automated logic doesn't do the right thing. (And there's a substantial chance these will be high stress situations where things don't work as planned; exactly NOT the situation in which you'd want the admin to start learning dmsetup manually, or having support staff dictate the commands over the phone...) I think this too is part of being user-friendly. Hi, I'm assuming several versions have been released since the "next version" mentioned in comment #1. Is this bug still relevant? Thanks, John Ben, how much of this, if any, do you think we still need? We already have equivalents to all the commands initially mentioned. |