[Linux-cluster] Lock Resources

[Ja S]

Hi, All:

I have downloaded "Programming Locking Applications"
written by Christine Caulfield from
http://sources.redhat.com/cluster/wiki/HomePage?action=AttachFile&do=view&target=rhdlmbook.pdf


I read it through, especially the DLM locking model.
It is very informative. Thanks Christine.

Now I have some questions about the lock resource and
wish to get answers from you.

1. Whether the kernel on each server/node is going to
initialize a number of empty lock resources after
completely rebooting the cluster? 

2. If so, what is the default value of the number of
empty lock resources? Is it configurable?

3. Whether the number of lock resources is fixed
regardless the load of the server?

4. If not, how the number of lock resources will be
expended under a heavy load?

5. The lock manager maintains a cluster-wide directory
of the locations of the master copy of all the lock
resources within the cluster and evenly divides the
content of the directory across all nodes. How can I
check the content held by a node (what command or
API)?

6. If only one node A is busy while other nodes are
idle all the time,  does it mean that the node A holds
a very big master copy of lock resources and other
nodes have nothing?

7. For the above case, what would be the content of
the cluster-wide directory? Only one entry as only the
node A is really doing IO, or many entries and the
number of entries is the same as the number of used
lock resources on the node A? If the latter case is
true, will the lock manager still divide the content
evenly to other nodes? If so, would it costs the node
A extra time on finding the location of the lock
resources, which is just on itself,  by messaging
other nodes?


If you need more information from me in order to help
me, or if you think my questions are not clear, please
kindly let me know.

Thank you very much in advance and look forward to
hearing from you.

Jas



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