>>> Lars Marowsky-Bree <[email protected]> schrieb am 22.04.2013 um 16:46 in >>> Nachricht <[email protected]>: > 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.
Hi! I'm not wanting to discuss this eternally, but from SLES11 SP1 to SLES11 SP2 for MD-RAID the default bitmap chung size changed dramatically: Where some RAID used something like 200 pages for the bitmap, it now uses 3 pages (when you recreate the RAID, of course). Naturally the granularity of much coarser now, but maybe considering TLB this is more efficient on today's hardware. Maybe a similar change would be beneficial for LVM mirroring... Regards, Ulrich > > > > 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 _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
