Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Fri, Nov 25, 2011 at 9:53 AM, Florian Haas <florian at hastexo.com> wrote: > On 11/25/11 06:23, Trey Dockendorf wrote: > > After reading the documents linked previously, most of the DRBD user > > guide and documents related to Pacemaker, I still have a few conceptual > > questions. > > > > First, I've seen lots of mention of the requirement to to sync the XML > > data for each VM. Is this necessary will KVM or Pacemaker be handling > > this? Right now I typically store all VM disks at /vmstore which has > > the same security context as /var/lib/libvirt/images. Do I also need to > > replicate the directory containing the domain XML files? > > Yes. You can do that by putting those into a separate directory in > /vmstore as well (or on NFS, for that matter), and then use > ocf:heartbeat:symlink to manage your symlinks from /etc/libvirt/qemu. Or > your can just use csync2 to keep the configurations in sync. > > > The other questions is do Pacemaker and other services for clustering > > live on the replicated servers or on external systems? As a follow-up , > > if they live on the replicated servers, do I have to take measures to > > ensure those services stay in sync? > > I'm not sure what you mean here exactly, but if your question boils down > to "do I run Pacemaker on my DRBD nodes?", then yes, definitely so. > > > Right now I have a good idea of how to structure all this, but just a > > few low level concepts I have yet to fully understand. So far I think I > > can achieve the necessary failover and live migration for the VMs using > > 2 servers with /vmstore replicated with DRBD. /vmstore will live on top > > of GFS2 to allow active/active operation. > > What do you use for fencing? > > Florian > > -- > Need help with DRBD? > http://www.hastexo.com/knowledge/drbd > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > Excellent, thanks for the clarification. Correct, I wasn't sure if Pacemaker lives on the DRBD nodes. With Pacemaker on the DRBD nodes, is there any syncing necessary or will CMAN handle that? I'm getting that from http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf. For fencing I would be using STONITH. Though that seems "extreme". Does STONITH essentially create a failure when the conflicting system is shutdown, such that services from it will be brought online on the healthy node? Also, one specific use case I haven't seen much information on is what it is that actually performs the VM migration in KVM once a node fails. Based on what I've read it would seem that's Pacemaker's job, but haven't seen that specific scenario mentioned yet. Thanks - Trey -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20111125/29deb55c/attachment.htm>