Re: [linux-lvm] clvmd interface question

[John DeFranco <defranco@cup.hp.com>]

Patrick Caulfield wrote:

>John DeFranco wrote:
>  
>
>>Hi, I'm looking for some information. I'm interested in learning more
>>about the clvmd daemon. I've search and found various pieces of info in
>>addition to looking at the code. Specifically I looking to for
>>information (a spec) on how one might be able to add a new cluster
>>manager plugin if you will (if that is even possible). I know that clvmd
>>interfaces with a couple of different cluster managers now but I'd like
>>to expland this if possible.
>>    
>>
>
>clvmd supports cman and gulm, it has it's own internal function switch that
>determines what to do for each cluster manager.
>
>To be honest it's not a good API as it was originally only designed to work with
>cman and the gulm support was bolted on later - so adding a new cluster manager
>might be a bit of work.
>
>Have a look at the bottom of LVM2/daemons/clvmd/clvmd-cman for the function switch.
>
>You'll also need to be aware that CMAN provides its own messaging system, which
>gulm does not. If your cluster manager provides a messaging system then I
>recommend you use it - otherwise you should be able to use the tcp-comms.c file
>with clvmd (that gulm support uses).
>
>Another way, that might be easier, is to patch clvmd with the libcman patch in
>head of cluster CVS (cluster/cman/lib/clvmd-libcman.diff) and write a library
>for your cluster manager that emulates libcman - that one is a nice simple API
>and it will be supported by future versions of cman too.
>
>  
>
Thanks for the info. I'll be looking into this.

-- 
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Cheers
   -jdf