[Lustre-discuss] command akin to "dump waiters"

Andreas Dilger adilger at sun.com
Wed Dec 2 21:06:39 PST 2009

On 2009-12-02, at 20:41, John White wrote:
> 	I wonder if lustre has a command akin to the GPFS `mmfsadm dump  
> waiters` that basically shows any threads stuck in a holding pattern  
> (for whatever reason, waiting on a lock, waiting on IO, etc) between  
> clients and the server host cluster.

I guess that depends on how "akin" you mean.  Lustre, in some sense,  
has less need for such functionality because the DLM is not as  
"distributed" as the GPFS one is.  Lustre only ever has a single  
server for any given set of resources - the MDT for inodes, and the  
OSTs for their own objects.  In contrast, GPFS locks migrate to the  
clients and are "served" from there, which makes it a lot more complex  
to debug.

It IS possible to dump the lock state of a server or client into the  
lustre debug log, via "lctl set_param ldlm.dump_namespaces=1; lctl dk / 
tmp/debug" but it may not be what you are looking for, since it will  
only show that node's lock state.  I've never seen the output of  
"mmfsadm dump waiters", so I can't comment on whether they are at all  

Cheers, Andreas
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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