18.01.2011 15:41, Vadym Chepkov wrote: ...
>>> >>> I have tried it myself, but concluded it's impossible to do it reliably >>> with the current code. >>> For the live migration to work you have to remove any colocation >>> constraints (group included) with the Xen resource. >>> drbd code includes a "helper" script - /etc/xen/scripts/block-drbd, but >>> this script can't be used in pacemaker environment, >>> because it is not cluster aware. And pacemaker is not handling this >>> scenario at the moment: >>> When Xen on drbd is stopped - both drbd nodes are secondary - makes >>> pacemaker "unhappy". >>> You need to have both drbd nodes as primary during migration only, >>> but if you specify master-max="2", then both drbd nodes are primary all the >>> time - disaster waiting to happen. >> >> Unless clustered LVM locking is enabled and working: >> # sed -ri 's/^([ \t]+locking_type).*/ locking_type = 3/' >> /etc/lvm/lvm.conf >> # sed -ri 's/^([ \t]+fallback_to_local_locking).*/ >> fallback_to_local_locking = 1/' /etc/lvm/lvm.conf >> # vgchange -cy VG_NAME >> # service clvmd start >> # vgs|grep VG_NAME >> >> Of cause, this may vary from one distro to another. > > unfortunately, this is not available on Redhat 5 and this is where Xen is > used, since Redhat 6, Fedora dropped Xen support. > But out of curiosity, how would clvmd prevent you from starting Xen VM on > both nodes accidentally? It will not. This is a job for CRM. It will just allow you to safely operate on LVM VG on both nodes - create, delete, activate, deactivate LVs (like ocfs2 allows you to safely operate on filesystem itself on both nodes). Although, you can use exclusive locks (vgchange -aey), but this will make live migration impossible. I also first tried to go with RHEL5, but it has number of unresolvable problems with cluster components (mainly - DLM has no support for userspace cluster stacks), so I switched to F13 and will probably try RHEL6 (or CentOS6). _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
