[Linux-cluster] DLM

[Mike Fedyk]

Patricio Bruna V wrote:

>El jue, 17-03-2005 a las 17:02 -0500, Daniel Phillips escribió:
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>>Hi Patricio,
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>>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?
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>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.
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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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