Hi, all

I have an idea of cluster lock with sanlock. However, I am not familiar with the principle detail of sanlock. This mail is sent to the expert of sanlock to discuss its feasibility.

My idea about the cluster lock:

1) Initialize the lockspace and resource at first.

2) Add the hostId of nodes into the lockspace after step 1.

3) Loop:

4)    If the node wants to acquire the cluster lock, “sanlock.acquire()” can be called. “sanlock.release()” will be called once the operation finished.

What about the feasibility of this idea?

I hava debuged the demo code of sanlock named ‘python/example.py’ step by step in two nodes(Node1, Node2). Demo code likes the following segment:

Demo code:

L1     import sanlock

L2     sd_path = "/dev/pool/"

L3     ids_file = sd_path + "ids_file"

L4     lease_file = sd_path + "lease_file"

L5     LEASE_NAME = "LEASE"

L6     sanlock.init_lockspace(sd_path, ids_file)

L7     sanlock.init_resource(sd_path, LEASE_NAME, [lease_file])

L8     host_id = 2                                            <-----different node has its own host_id here.

L9     sanlock.add_lockspace(sd_path, host_id, ids_file)

L10   _sanlock_fd = sanlock.register()

L11   sanlock.acquire(sd_path, LEASE_NAME,[lease_file], slkfd=_sanlock_fd)

L1~L8 are executed in node1 and node2.

Execute in same time : L9 cannot be executed in the same time of these two nodes and one node would fail.

Execute one by one  :When node1 was added its hostId into the lockspace successfully first, the add_lockspace of node2 would overwrite the lockspace in “ids_file” without any exception. There are only one node which writes its timestamp into its sector.

Appreciate for your reply.

Thank you very much.

Qi