[Linux-cluster] optimising DLM speed?

Alan Brown ajb2 at mssl.ucl.ac.uk
Thu Feb 24 23:14:35 UTC 2011

On 24/02/11 22:40, Scooter Morris wrote:
> Hi all.  After two tries, we've modified our cluster so that all nodes 
> have increased their dlm hash table sizes to 1024.  Initially, I put 
> the echos in /etc/init.d/gfs2, but it turns out that /etc/init.d/gfs2 
> is sort of a no-op: /etc/init.d/netfs mounts the gfs2 filesystems 
> before /etc/init.d/gfs2 is ever called, so the echos need to be before 
> netfs.

I created a new init.d script to apply the values immediately after cman 
is started - see attached files.

> At any rate, we have noticed a significant perceived improvement in 
> overall performance of the systems.  Where before, it was common to 
> see imap process in D wait -- sometimes hanging for long periods of 
> time -- we have not seen that at all since updating the hash table 
> size.  So far, so good!

How much ram have you got and which version of gfs2 are you running?

vermagic:       2.6.18-238.1.1.el5 SMP mod_unload gcc-4.1

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