[dm-devel] [PATCH 3/6] libmultipath: add overrides section to multipath.conf

[Marian Csontos]

On 01/13/2015 01:01 AM, Sebastian Herbszt wrote:
> Hello Christophe,
>
> Christophe Varoqui wrote:
>> Hi,
>>
>> the precedence chain is :
>>
>> multipaths > user-specified per-device > default per-device > default
>>
>> The issue adressed by Ben's patch would not be solved by your suggestion,
>> as far as I can see. The proposed override section is just a way not repeat
>> a per-device in each multipath (insane) or device (tedious) section.
>
> care to explain why setting the precedence to
>
> multipaths > user-specified per-device > default > default per-device
>
> would not fix the issue?

It may very well "fix" the issue but having global default overriding 
drive-specific default seems to me as wrong as breaking compatibility by 
such change which would likely introduce more issues.

-- Martian

>
> Lets assume the following default device and user configuration:
>
> .vendor        = "COMPELNT",
> .product       = "Compellent Vol",
> .pgpolicy      = MULTIBUS,
> .pgfailback    = -FAILBACK_IMMEDIATE
> .no_path_retry = NO_PATH_RETRY_QUEUE,
> .checker_name  = TUR
>
> defaults {
> 	no_path_retry fail
> }
>
> devices {
>          device {
>                  vendor "COMPELNT"
>                  product "Compellent Vol"
> 		path_grouping_policy "group_by_prio"
> 	}
> }
>
> multipaths {
> 	multipath {
> 		wwid 1234
> 		failback 15
> 	}
> }
>
> The default section should change no_path_retry from "queue" to "fail".
> The device section should change path_grouping_policy from "multibus"
> to "group_by_prio" for "COMPELNT/Compellent Vol".
> The multipath section should change failback from "immediate" to 15
> for wwid 1234.
> The path_checker would still be "tur".
>
> Is this not what the "overrides" patch intended?
>
> Sebastian
>
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