[dm-devel] Re: multipathd: sdc: readsector0 checker reports path is down
Ray Van Dolson
rvandolson at esri.com
Thu Jan 8 20:10:09 UTC 2009
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?
> >
> > 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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