[dm-devel] Multipath and LVM (lvdisplay takes 30Secs)

Moger, Babu Babu.Moger at netapp.com
Wed May 16 16:47:33 UTC 2012


> -----Original Message-----
> From: dm-devel-bounces at redhat.com [mailto:dm-devel-
> bounces at redhat.com] On Behalf Of ml ml
> Sent: Wednesday, May 16, 2012 3:42 AM
> To: device-mapper development
> Subject: Re: [dm-devel] Multipath and LVM (lvdisplay takes 30Secs)
> 
> Hi,
> 
> >> multipath -l -v 2
> >> SAN (3600a0b80001f7557000032864ce4aff3) dm-0 IBM,1722-600
> >> size=250G features='1 queue_if_no_path' hwhandler='1 rdac' wp=rw
> >> |-+- policy='round-robin 0' prio=-1 status=active
> >> | `- 2:0:1:0 sdb 8:16 active undef running
> >> |-+- policy='round-robin 0' prio=-1 status=enabled
> >> | `- 3:0:1:0 sdd 8:48 active undef running
> >> `-+- policy='round-robin 0' prio=-1 status=enabled
> >>   `- 3:0:0:0 sdc 8:32 active undef running
> >
> > Prio is showing -1.  May be your path grouping policy and prio handler is not
> set right.
> > I would set it correctly and then test it again. Here is how I would set it in
> multipath.conf.
> > path_grouping_policy    group_by_prio
> > prio                                    rdac
> >
> 
> Right now i am using "path_grouping_policy    failover". See below for
> the full config file.
> Since i want failover/redundancy. In this case i really want
> "path_grouping_policy    group_by_prio"?

Yes, With group_by_prio  you will still have failover/redundancy. 

> 
> Here is the full config file:
> 
> 
> blacklist {
>         devnode "sda"
>         devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
>         devnode "^hd[a-z][[0-9]*]"
> 
> }
> 
> defaults {
>         user_friendly_names     yes
>         udev_dir                /dev
>         polling_interval        10
>         verbosity               0
>         path_grouping_policy    failover
>         #path_grouping_policy    group_by_prio
>         #prio                    rdac
> 
> }
> 
> multipaths {
>        multipath {
>                wwid                    3600a0b80001f7557000032864ce4aff3
>                alias                   SAN
>                path_grouping_policy    failover
>                path_selector           "round-robin 0"
>                failback                manual
>                rr_weight               priorities
>                no_path_retry           5
>                rr_min_io               100
>        }
> }
> 
> devices {
>        device {
>                vendor                  "IBM"
>                product                 "1722-600"
>                path_grouping_policy    failover

I will recommend to add following lines here.
path_grouping_policy    group_by_prio
prio                                    rdac

>        }
> }
> 
> 
> 
> Thanks,
> Mario
> 
> --
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