Hi, We've recently done some re-engineering to the dlm to make it more easily adaptable to other environments. The dlm is now configured/controlled from user space using sysfs. It depends on nothing in the kernel that's not already there and it's completely agnostic about who or what is controlling it from user space. (Another unrelated change is that it now uses SCTP intead of TCP.) Someone or thing in user space now just tells the dlm who the nodes are who are using it. This happens per-lockspace, of course, as different groups of nodes may be using different lockspaces. A new command line program, dlm_tool, can be used to set up the dlm manually in which case it depends on no other software (much like using dmsetup with device-mapper.) Of course, some sort of user-level membership system would usually be used to control the dlm instead of dlm_tool, but that's completely variable now (like using either LVM2 or EVMS over device-mapper). Here are instructions on how to use dlm_tool. It also illustrates what the responsibilities of a membership system would be when dealing with the dlm: http://sources.redhat.com/cgi-bin/cvsweb.cgi/cluster/dlm/doc/dlm_tool.txt?cvsroo t=cluster We're interested in some feedback -- does this make the dlm more useful for you and the general public? If not, what might? We'd like to see this dlm be used beyond GFS and CLVM. A roadblock in the past was the disparate clustering and membership managers. While consolidation continues slowly on that front, the dlm should be able to move ahead by remaining agnostic. This also clears the way for submitting the dlm to be included in the main kernel. We're currently working on making the code suitable for that level of inspection after which (very soon) we'll send it out as a set of kernel patches. new dlm kernel code: http://sources.redhat.com/cgi-bin/cvsweb.cgi/cluster/dlm-kernel/src2/?cvsroot=cl uster dlm_tool to configure/control the dlm manually: http://sources.redhat.com/cgi-bin/cvsweb.cgi/cluster/dlm/?cvsroot=cluster GFS (which uses the in-kernel dlm locking API) will be configured and controlled from user space in the same way, remaining agnostic about who or what is driving things. An external membership system would typically be used to control both the dlm and gfs since they both require very similar control input. It's worth noting that the dlm remains a general purpose, VMS-like dlm, completely independent from GFS or any other application. -- Dave Teigland <teigland@xxxxxxxxxx>
