> - what is the logic redhat is using to create the WWID
> and what are the fields involved
see the multipath.conf samples coming with rpm : the "getuid_callout" keyword is there to let users change the multipath naming poilicy. By default paths are identified as part of the same multipath using the VPD page 0x83 identifier, which is a standard. This unique id is used a multipath name if "user_friendly_names" are not enabled. And you still have to choice to use the "alias" keyword to name specific multipaths.
> - I am trying to test with the shared luns (devices) between
> two nodes. How i will identify the device id in multipath.
I'm assuming you're concerned with EMC hardware, because of the terms you use (device id, ...). Following response mmight be out-of-context if you're not.
There I would advise you use syminq as a getuid_callout ... but no. syminq slow, bloated, and offers no control on its output. You'd be better server by a script using syminq to generate your configlets :
multipath {
wwid 1234
alias devid
}
> Though as per Redhat , they are telling WWID is the identifier.
> But how i will identify the device id in the WWID?
> It is very much needed specially for shared luns. In PowerPath,
> generally all the devices are identified by the
> lun id /device id then ,
> I use the Pseudo name (linux), for configuring the devices. I will
> assume that WWID is similar as Pseudoid. If not, pl. correct me.
wwid-based multipath names are indeed garanteed to identify the same device across a cluster accessing the same array. Beware though, replicated devices (R2) will surely have different ids and different wwids ... you's need to use "alias" to have geocluster multipath names coherency.
> - Where can i match the device id in the WWID..
syminq
>
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