Hi Lucas,
Lucas Brasilino wrote:
> Hi
>
> I don't know if I'm misundertanding something. I've got an DS4700 and I'm
> switching from RDAC[1] to multipath, since it's natively supported in
> the distribution I use
> here (SLES 10 SP2).
>
> Since RDAC[1] works perfect, I'm trying to use 'rdac' priority in multipath.
>
> My /etc/multiconf.conf is quite tiny, since I'm building it step-by-step :-) :
>
> blacklist {
> devnode "^sda[0-9]*"
> }
>
> defaults {
> user_friendly_names yes
> prio rdac
> path_checker tur
> }
>
> multipaths {
> multipath {
> wwid 3600a0b8000327b900000107549f85224
> alias mpath0
> }
> }
>
> I think that using 'prio rdac' makes multipath to use 'mpath_prio_rdac' tool.
>
> # multipath -v2 -ll
> mpath0 (3600a0b8000327b900000107549f85224) dm-0 IBM,1814 FAStT
> [size=140G][features=1 queue_if_no_path][hwhandler=1 rdac]
> \_ round-robin 0 [prio=6][active]
> \_ 9:0:0:0 sdb 8:16 [active][ready]
> \_ round-robin 0 [prio=1][enabled]
> \_ 10:0:0:0 sdc 8:32 [active][ghost]
>
> So the first path has priority 6, as I can confirm:
>
> # mpath_prio_rdac /dev/sdb
> 6
> # mpath_prio_rdac /dev/sdc
> 1
>
> After the first path (prio=6) failure I get:
>
> # multipath -v2 -ll
> sdb: rdac prio: inquiry command indicates error
> mpath0 (3600a0b8000327b900000107549f85224) dm-0 IBM,1814 FAStT
> [size=140G][features=1 queue_if_no_path][hwhandler=1 rdac]
> \_ round-robin 0 [prio=0][enabled]
> \_ 9:0:0:0 sdb 8:16 [failed][faulty]
> \_ round-robin 0 [prio=1][enabled]
> \_ 10:0:0:0 sdc 8:32 [active][ghost]
>
> Ok.. working great, activating the second path. But after the faulty
> path is restored:
>
> # multipath -v2 -ll
> mpath0 (3600a0b8000327b900000107549f85224) dm-0 IBM,1814 FAStT
> [size=140G][features=1 queue_if_no_path][hwhandler=1 rdac]
> \_ round-robin 0 [prio=2][enabled]
> \_ 9:0:0:0 sdb 8:16 [active][ghost]
> \_ round-robin 0 [prio=5][active]
> \_ 10:0:0:0 sdc 8:32 [active][ready]
>
> Second path is now priority!!! And of course does not fails back! By
> the way, my LUN is configured in
> DS4700 in sort a way that the first path *is* the path to preferred controller.
>
> I think path priorities should not change. If so first path goes back
> to 'active' status.
> Am I misunderstanding something ? Or messing things up?
>
You are using an old version of multipathing for SLES10 SP2.
This had a bug triggering priority inversion on RDAC.
Please update to the latest version.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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