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Re: [Linux-cluster] DLM



Patricio Bruna V wrote:
El jue, 17-03-2005 a las 17:02 -0500, Daniel Phillips escribió:
  
Hi Patricio,
    

  
Perhaps you meant, how does your program ask for a lock?  Or how does 
DLM get a lock from a nonlocal machine?  From userspace, you go through 
a library that presents an interface similar to ancient Vaxcluster, and 
later, IBM's OpenDLM.  (But somewhat more complex because of the 
hierarchical locks feature and a few other wrinkles.)  These API calls 
are translated into socket messages to and from the in-kernel DLM.  The 
local DLM consults its lock directory to find out which machine masters 
the lock and requests the lock from that machine, which then tries to 
get the lock based on its knowledge of current holders, if any.

Does that answer your question?

    
Daniel,
	thx for the answer, but i have another question.
	Its necesary that the programs be build agains or with the dlm api?

because if they need to, i dont see the benefits of dlm.
  
My understanding of DLM is that it sits above the standard FCNTL locks, and with DLM in place, the locks are cluster wide with the standard locking APIs.  I do not know if DLM works with flock though.

Mike

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