[dm-devel] Designing a new prio_callout
Hannes Reinecke
hare at suse.de
Mon Jul 30 06:31:01 UTC 2007
Ethan John wrote:
> Thanks for the heads-up about ALUA. We're looking into it.
>
> What is the purpose of the custom mpio_prio_* applications that ship
> with open-iscsi if not to handle multipathing?
>
It is. mpath_prio_* are the priority callouts for multipathing.
They determine the layout of the multipath map.
Theory is that mpath_prio_* will return the priority for a
given path in relation to the entire multipath layout.
If used with 'group_by_prio' all paths with the same
priority will be grouped into one multipath group, and
the group with the highest priority will become active.
When all paths in a group fail, the group with the next
highest priority will become active. Additionally some
failover command (as determined by the hardware handler)
may be send to the target.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare at suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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