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Re: [Linux-cluster] rgmanager vm.sh using virsh under RHEL5.4




Le 2 nov. 2009 à 20:05, Lon Hohberger a écrit :

On Mon, 2009-11-02 at 16:44 +0100, Alain RICHARD wrote:

a) use_virsh = 1 per default
b) that if your resource have a path attribute, vm.sh automatically
revert to use_virsh=0, even if you hard code use_virsh=1 !
c) there is no option to indicate the xml file that virsh use to
create the vm. It always tries "virsh create name" where name is the
vm name.

The point a) is a little bit silly because if you have a RHEL 5.3
cluster that is using xm configuration files, your vm will no longer
launch after upgrade because it tries to do a "virsh create name"
instead of "xm create name". It would have been probably cleaner to
have "use_virsh = 0" per default to keep compatibility.

Libvirt's Xen mode loads config files from /etc/xen.  When you run
'virsh start foo' it will look for the config in /etc/xen which defines
the virtual machine named 'foo'.

So, effectively, either what you said above works for me or I don't
understand your problem.  Both 'xm' and 'virsh' modes work on Xen
domains in 5.4 (assuming you don't have a path attribute set):

 http://pastebin.ca/1653460

Did you mix 5.3 libvirt with 5.4 rgmanager or something?  If so, I'd
simply keep using the vm.sh from rgmanager in 5.3.


I am sorry about that one : effectively virsh start xxx is able to read xen format config file and convert it on the fly in xml. It is not documentented anywhere, but I just tested that virsh start works.

The point b) will add compatibility to people that use the path
attribute in order to store vm conf files in a place shared by all
members of the cluster (gfs2 or nfs directory for example). It would
have been clearer to document this feature because it is a little bit
magical to see a resource with use_virsh=1 use in fact xm and not
virsh !!!

You can't use "path" with virsh.  You are correct, though - it should
produce an error if someone explicitly sets use_virsh="1" with a path=
also set.  The two options can not be used together.


no currently if the path is defined, use_virsh is silently forced to "0" in the script.

On making "virsh" mode more usable...

virsh supports 2 things:
 - Loading something by -name- from /etc/libvirt/qemu (or /etc/xen),
and
 - Defining transient virtual machines from a -file-

vm.sh when using virsh in 5.4 supports the former, but not the latter.
Federico Simoncelli wrote a patch to allow the latter for STABLE3:

http://git.fedorahosted.org/git/?p=cluster.git;a=commit;h=ea90559c936792e22576cac7a0bd0a2a50573426



yes, this is this one I hope to see backported under RHEL5.x.

The point c) is very silly, because it restricts the configuration to
be loaded from /etc/xen even for kvm !

Correct.  Well, /etc/libvirt/qemu for kvm, but... There's no way to
define alternate locations for VM config files in rgmanager from RHEL
5.4.


Also their is no problem to use a "virsh create /path/to/file.xml"
under RHEL 5.4 and I have found out that the cluster 3.0 stable branch
have a new vm.sh file using an xmlpath attribute to solve this
problem. Why this version was not back ported to RHEL 5.4 ? Is there
any plan to do it ?

No, but it sounds like there should be.


Should I open a case under bugzilla to ask for the backport ?

Regards,

-- 

Alain RICHARD <mailto:alain richard equation fr>

EQUATION SA <http://www.equation.fr/>

Tel : +33 477 79 48 00     Fax : +33 477 79 48 01

E-Liance, Opérateur des entreprises et collectivités,

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