The OpenDLM Project
OpenDLM is a distributed lock manager. It has interfaces for use at both user and kernel level.
We started from a very good starting point with IBM's DLM, and are
extending it to fit the needs of the various different types
of clusters. One eventual goal is to be a reference
implementation for the OCF locking API (once it is
standardized). Another is to be used for inter-node lock
support for OpenGFS, and perhaps other clustered filesystems.
RedHat invites us to a face-to-face technical meeting with GFS and cluster component engineers, to be held on July 29 and 30, 2004, in Minneapolis. Anyone interested is welcome to attend this rare opportunity (limited to first 50 people, first-come-first-serve). For more info, contact RedHat's Daniel Phillips.
RedHat open-sources GFS, along with other cluster components (including a DLM)! Both 2.4 (GFS 6.0, lacks DLM) and 2.6 (current CVS) versions are available for download. RedHat Cluster project page is here. A good doc about most of the components is here.
Changes have recently been checked in to the OpenGFS project to support OpenDLM as the inter-node lock manager.
OpenDLM has a few significant advantages over OpenGFS' memexp inter-node lock manager, primary ones being no single point of failure, and reduced LAN traffic when managing locks.