[Pacemaker] Searching for a viable Debian solution

[Quentin Smith]

Hi Paul,

Current clvm actually supports multiple locking schemes, including both 
the old redhat cluster stack and modern corosync/openais. We use Ubuntu 
Hardy with backported corosync and clvm packages, and it works pretty 
well. Hand-backporting is not for the faint of heart, though.

--Quentin

On Sat, 24 Apr 2010, Paul Gear wrote:

> Hi folks,
>
> Over the last several days i've been reading, asking questions (special 
> thanks to beekhof, tserong, fghass and the other kind folks on #linux-ha 
> putting up with my questions), and experimenting with my test setup, and i'm 
> yet to find a viable combination of options for creating a VM cluster on 
> Debian.
>
> The preferred components of my setup are:
> - Debian lenny
> - Xen VMs
> - OCFS2 on an iSCSI NAS for shared storage
> - whatever openais/corosync/pacemaker combination will do the job
> - I'd like to have live migration of VMs but it's not essential
>
> The point of my setup is to have a test cluster with which i can play (and 
> run my own home network) without breaking the ones i have to support at 
> customers.  I work with small businesses, educational institutions, and 
> non-profits, none of whom have the means to support a fully working test 
> configuration, or to buy time from big name consultants who can employ 
> full-time clustering specialists.
>
> My experiments thus far have been with corosync & pacemaker from 
> http://people.debian.org/~madkiss/ha/, and with libvirt from lenny-backports.
>
> When i tried the latest versions of corosync & pacemaker in the above repo, i 
> was able to get the cluster running appropriately, but when i tried to add 
> the DLM clone resource, i got this error: "controld[3526]: ERROR: Setup 
> problem: Couldn't find utility dlm_controld.pcmk".  So it seems that OCFS2 is 
> not viable with the current state of the corosync/openais/pacemaker stack. 
> I've investigated a couple of alternatives to my preferred list, including:
>
> - cLVM - requires the Red Hat cluster stack and conflicts with the current 
> corosync/openais/pacemaker versions.  This would be my preferred solution if 
> it were possible to use LVs from the same VG on different nodes 
> simultaneously.  I'm not sure whether this is possible, because the cLVM 
> documentation is almost non-existent, and i couldn't find answers to any of 
> my big questions.
>
> - libvirt with iSCSI as the backend for the storage pool.  I've tried this 
> and it looks promising, but it appears non-functional on iSCSI storage 
> backends at the moment.  I get this message when i try to create a volume: 
> "libvirtd: ... error : storageVolumeCreateXML:1301 : this function is not 
> supported by the hypervisor: storage pool does not support volume creation"
>
> I substituted KVM for Xen, and the result was the same.
>
> So, the question remains: what is a viable HA stack for Debian with 
> virtualization and shared storage?  I'm happy to switch technologies where 
> it's necessary; here are the things i would be willing to try if necessary:
>
> - Different clustered file storage setup.  What are the possibilities? GFS2? 
> DRBD seems feasible, but it doesn't actually solve anything in the above 
> equation, so i'd rather keep the iSCSI NAS.
>
> - Switching distros?  Possible - my order of preference: Debian squeeze, 
> Debian sid, Ubuntu lucid, openSUSE 11.2, CentOS 5.4.
>
> - Switching cluster stacks?  I've worked with clusters on HP-UX, NetWare, 
> OES/Linux 1, heartbeat 1, and heartbeat 2, so i'm sure one more change won't 
> kill me, but the more similar in feel it is to pacemaker or heartbeat 2, the 
> better.  If using non-integrated OCFS2 cluster membership and an older 
> openais or heartbeat version is viable, i'm happy to look at that as well, 
> although obviously i'd rather go forward than backward.
>
> - Switching VM technologies?  I guess KVM, VirtualBox, or OpenVZ would be 
> viable, but again, it doesn't seem to solve much in the current scenario.
>
> What's the path of least resistance here?
>
> Thanks in advance,
> Paul
>
>
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