On 2013-04-22T15:18:20, Ulrich Windl <[email protected]> wrote:
> That's where OCFS2 comes in: When hosting Xen-VM images, multiple (we just > use the trivial two-node cluster) hosts may acess one LV (i.e.: one > filesystem), while access (if OCFS2 does allocate the data in big extents) to > specific areas is mostly local to one node. Sure. Yes, this thin-provisioning is one of the most important features in OCFS2 for the virtualization use case. > I don't know how mirroring works at the moment, but I guess one node > does the mirroring job for a whole LV. It would be probably better if > the mirroring of one LV could be distributed among nodes so that each > node would mirror the data it accesses. Then when idle, some task > could do the rest (that is out of sync, if any). No, actually, all nodes write directly to disk. But access to the mirrorlog has to be synchronized, and the locks to invalidate read pages so that no stale data is presented. > > At least not for released code, no, this is not the case. > > ftp://sources.redhat.com/pub/lvm2/ - last release is from October. And > > it doesn't improve this much at all. > Specifically I meant "mirrorlog=mirrored" described for RHEL 6.1, vs. SLES': > > # lvcreate --mirrorlog mirrored -m 1 --name cLV1 -L 8G cVG > Log type, "mirrored", is unavailable to cluster mirrors > > Of couse I couldn't check from the docs whether this would work for RHEL. The mirrorlog=mirrored works only for local mirrors with RHEL 6.1 too, just like with SLES so far. The cluster functionality is not present upstream: http://article.gmane.org/gmane.linux.lvm.devel/4620/match=mirrored Dong Mao from the SLE HA development team developed the necessary patches to cmirrord to allow this to work in a cluster context (available with SLE HA 11 SP3, feel free to test it as part of your beta program participation). See http://comments.gmane.org/gmane.linux.lvm.devel/8891 how much response this generated from the upstream/RHT development community. Seriously, you're misdirecting this particular rant. Regards, Lars -- Architect Storage/HA 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 [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
