Hi Patricio, I'll take a run at answering this, since the DLM engineers are in far away timezones. On Thursday 17 March 2005 16:39, Patricio Bruna V wrote: > how does dlm comunicates with the other nodes? It uses a custom-made network protocol called PF_CLUSTER, which is nominally part of cman. This protocol is similar to UDP but with delivery (and ordering?) guarantees. > how dlm ask for a lock? The short answer: DLM does not ask for locks. DLM is the boss and takes locks as it sees fit. 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? > im asking this because i want to know what happens if dlm comunicates > trough the LAN (or crossover) and need to ask for a stupid amount of > locks (like 10000000) and the lan (or crossover ) its fully loaded > with other kind of traffic Try it and see what breaks :-) Regards, Daniel
