[Linux-cluster] When using GFS+DLM, will DLM manage the locks on journals?

Bob Peterson rpeterso at redhat.com
Thu May 15 13:23:10 UTC 2008

On Wed, 2008-05-14 at 17:27 -0700, Ja S wrote:
> > >> My understanding is that there is no locking on
> > the
> > >> journals across 
> > >> nodes except when a node gets fenced and it's
> > >> journal needs to be 
> > >> replayed to ensure data is consistent. Each node
> > has
> > >> it's own journal.


The journals in GFS are special files with cluster-wide locks
("glocks"), so inter-node locking still applies.  IIRC, all
nodes keep a "read" lock on all the journals.  However,
every node is assigned a primary journal and uses that journal
only, under a "write" lock which means there is no lock
contention except during recovery situations where a journal
has to be replayed.


Bob Peterson
Red Hat Clustering & GFS

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