[dm-devel] Upcall prioritizer for multipath

[Oliver Mangold]

I'm working with JBODs and would like to access the disks inside through 
dm-multipath. For performance reasons I would like to use to prioritizer 
to pin individual disks to different paths. For testing purposes this 
can be done with the weighted_path prioritizer, but for production use 
this is unsatisfactory, as neither the device name nor the SCSI address 
are persistent over reboots. Thus I wrote a new, simple prioritizer to 
call an external program to determine what the prio should be. I would 
like to ask if there is interest to include this (or something similar) 
upstream (see attached patch).

Remark: After I did this, I've seen the wwn regex mode in the upcoming 
0.6 version, which would also provide a solution to the problem I 
started out with. But using this would still means one had to recreate 
multipath.conf each time one replaces a failed disk, so I still believe 
having an external upcall makes sense in some situations.

Any thoughts?

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