[Ocfs2-users] dlm questions

[Charlie Sharkey]

Thank you for the prompt reply.

Some error condition questions ...

Say in a 4 node cluster one node has a dlm lock. Is 
there any way to remove that lock from another node ?
 
If that node that had the lock suddenly goes down, will 
it's lock be removed after a timeout value, or only when the
node reboots and rejoins the cluster ?

If the failing system that had the lock was replaced while
it was down, would the replacement system still unlock 
the dlm lock or would the contents of the previous (failing) 
system's /dlm/domainname directory have to be transferred to the 
new system ?
 

Thanks again,

charlie


-----Original Message-----
From: Sunil Mushran [mailto:Sunil.Mushran at oracle.com] 
Sent: Monday, January 07, 2008 2:49 PM
To: Charlie Sharkey
Cc: ocfs2-users at oss.oracle.com
Subject: Re: [Ocfs2-users] dlm questions

Only way this can work is if all 4 nodes are part of the same cluster as
that is a prerequisite for the nodes to be in the same dlm domain. And
nodes have to be part of the same domain inorder to coordinate locking
on a resource.

Meaning sharing a volume between two clusters is asking for corruption.
Actually, I don't think you will be able to get this to even work as
either mount will fail or heartbeat will fence with the "another node is
heartbeating in my slot".

Charlie Sharkey wrote:
> I have an application I run on the nodes of a cluster. This 
> application used the dlm for file locking between the nodes by calling

> o2dlm_initialize() to create a domain, and then o2dlm_lock() and 
> o2dlm_unlock() to lock/unlock files. This works fine, and the locks 
> are seen by the other nodes.
>
> I was wondering on the viability of two clusters accessing the same 
> volume, and seeing each others locks.
>
> Say I have two (2 node) clusters, A and B. Each cluster is on a 
> private network within itself, and they are identical. This means each

> cluster will have a system host1 on 10.1.1.1 and a system host2 on
10.1.1.2 .
>
>   1. first of all, would this configuration even work ? If not,
>      would it work if the clusters had different cluster names, 
>      host names, ip addresses ?
>
>   2. can a node on cluster A see a dlm lock from cluster B ?
>      note there is no IP connection between the clusters.
>      
>   3. is there any way to make one cluster aware of a different cluster
>      that is ip connected (one with a different cluster name, host 
> names,
>      ip addresses, same/different dlm domain names) ?  
>
> Thank you,
>
> charlie
>
> _______________________________________________
> Ocfs2-users mailing list
> Ocfs2-users at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-users
>