On Thu, 2009-01-08 at 12:10 -0800, Ray Van Dolson wrote:
> On Thu, Jan 08, 2009 at 11:58:52AM -0800, Chandra Seetharaman wrote:
> >
> >
> > On Thu, 2009-01-08 at 11:31 -0800, Ray Van Dolson wrote:
> > > I'm still getting the hang of iSCSI and multipath, so bear with me if
> > > this is a FAQ that I've missed...
> > >
> > > I have a host attaching to an MD3000i via iSCSI/dm-multipath that is
> > > working but showing a lot of the following errors in syslog:
> > >
> > > multipathd: sdc: readsector0 checker reports path is down
> > you should be using the rdac path checker. In addition to that you
> > should be using rdac hardware handler and tpc priority checker.
> >
> > If you have and entry for your MD3000i in /etc/multipath.conf, replace
> > it with this. If not add this
> > -------------------
> > devices {
> > device {
> > vendor "DELL"
> > product "MD3000i"
> > hardware_handler "1 rdac"
> > path_checker rdac
> > failback immediate
> > path_grouping_policy group_by_prio
> > no_path_retry queue
> > prio_callout "/sbin/mpath_prio_tpc /dev/%n"
> > }
> > }
> > ---------------------
> >
> > After this change you have to do:
> > - multipath -F
> > - service multipathd restart
> >
> > Let me know how it goes.
>
> This appears to have done the trick. So, I guess the default path
> checker is readsector0 and rdac is another method -- I imagine it
> directly talks to my MD3000i to determine path status?
Yes, it sends a C9 inquiry to the storage controller and determines the
state.
>
> > >
> > > My initial impression is that sdc is likely the "passive" path (for
> > > failover) whereas sdd is my active path:
> >
> > yes.
>
> Thanks much!
>
> Ray
>
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