Red Hat Bugzilla – Bug 187534
Cannot change rr_min_io without rebooting
Last modified: 2010-01-11 21:24:47 EST
Description of problem: Cannot change rr_min_io on the fly Version-Release number of selected component (if applicable): U3 How reproducible: Always Steps to Reproduce: 1. change rr_min_io in multipath.conf and re-run multipath 2. OR reload table with changed weights: [root@clu1 mnt]# dmsetup table mpath2 0 122880000 multipath 0 0 1 1 round-robin 0 2 1 8:32 1000 8:80 1000 [root@clu1 mnt]# echo "0 122880000 multipath 0 0 1 1 round-robin 0 2 1 8:32 100 8:80 100" | dmsetup reload mpath2 [root@clu1 mnt]# dmsetup table mpath2 0 122880000 multipath 0 0 1 1 round-robin 0 2 1 8:32 1000 8:80 1000 Note that the rr is still 1000 1000
reload doesn't change the table until you issue a 'resume'
Workaround: You need to unmount the filesystem, and stop LVM. Once the map is unused you can flush it and rebuild it... Sample commands: umount /mnt/TEST/ vgchange -an multipath -f mpath3 multipath vgchange -ay mount /mnt/TEST/ note you can localize this by giving vgchange an argument to a vg instead of affecting all vg's on the system...
It's possible to fix this to work like change from multibus to failover, but it's not straightforward. If people are o.k. with it, I'd rather just document this, and fix it when we do the next pull from multipath upstream.
I think that is fine. we should make sure the documentation uses vgchange with a named group as argument so people don't run vgchange -an and lose other volumes. The other piece we should document is using vgchange -aln with clvm so you can change the min io's on, say, a gfs volume...
You are now able to change rr_min_io just like you can change multibus and failover.
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
Devel ACK - need QE ACK
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 the 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-2007-0256.html