On 2011-05-19T10:36:04, Ulrich Windl <ulrich.wi...@rz.uni-regensburg.de> wrote:
> reading the SFEX wiki page, I felt the main reason for confusion is the > description of SFEX itself: "SFEX is resource which control ownership of > shared disk" That is true - that is the effect if properly configured and integrated into the dependency tree of Pacemaker. > As my reading suggests, that is not true. Instead the truth seems to be: > "SFEX is a resource that controls ownership of shared resources by using a > shared disk" > > So you see why I thought a raid needs two SFEX devices. Knowing that you can > control multiple resources with one SFEX device, results in a different > solution. The integrity of all resources is already implicitly protected via fencing. sfex effectively only makes sense where fencing isn't available; both are advisory in the sense that they rely on proper operation of the policy engine. > I'll attach my handwritten comments on the page (200kB of PDF, sorry for > that!), so maybe someone can update the wiki page. (If you grant me write > access, I could do as well, but I don't know whether I'm right). I do appreciate your feedback, but reading handwritten notes really isn't the best way to go about this. You can register for the wiki yourself, though. > Can I say that an SFEX resource is a mutex lock, and the "-n" parameter > specifies the number of such locks (and not the number of hosts accessing the > lock)? SFEX provides advisory locking, and the locks are enumerated, yes. At sfex_init time, -n specifies the number of slots for locks on the device. sfex_lock supports the -i switch to select one of these slots; mapping between locks to protected services is an admin task. It doesn't support shared locks, it is exclusive-only. Regards, Lars -- Architect Storage/HA, OPS Engineering, Novell, Inc. SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg) "Experience is the name everyone gives to their mistakes." -- Oscar Wilde _______________________________________________ Linux-HA mailing list Linux-HA@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems