[dm-devel] [RFC] [PATCH] add serial keyword to the weightedpath prioritizer

[Hannes Reinecke]

On 08/01/2016 02:25 PM, Christophe Varoqui wrote:
> Or we could honor arythmetic expressions like "5*alua+weightedpath",
> giving users more control about preferences (and more opportunities to
> step on their toes, sure).
>
Ugh. No.
You still would need to know which values the 'alua' (or any 
prioritizer) will be returning.
ATM there is no guarantee nor even advise which values a prioritizer 
should return. Which in itself is a good idea IMHO.

> Another idea, less invasive if possible, but less versatile :
>
> - Merge the alua prioritizer into the weightedpath prioritizer, given
> the optimized/non-optimized and other ALUA states are available in the
> path struct and have their snprint_path_* function and %wildcard.
>
Hmm. I still prefer the 'stacked prioritizer' approach, what with it 
being far more flexible.

> - Then weightedpath prio_args can be extended to support additive
> priorities, like "alua <optimized state>:<... state> 10 serial foo 20"
>
Which again would require us to define the possible return values from 
the alua (or any other handler).

Cheers,

Hannes
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