Hello, is there any pointer about how to set up a cluster of Qemu/KVM hosts? I'm on F11 x86_64 for the hosts. I read requirements for KVM migration in general highlighted at http://www.linux-kvm.org/page/Migration but I keep having doubts, in particular regarding libvirt configuration in cluster environments... Some questions about libvirt configuration: - /etc/libvirt/qemu/networks do the files inside here be identical between hosts (default.xml and other custom configured network ones)? What are the uuid tags into the xml for? Do they have to be identical for clusters or do they have to be absolutely different for a sort of "identification" of host (as the term seems to suggest)? If I have guests that use virbr0 and use dhcp for their network config, and want two different qemu/kvm hosts able to migrate these guests between them, need to have same config or what? - the same for storage configuration and other parameters.
Suppose I clone a pre-config F11 host configured with libvirt, and suppose I have to differentiate uuid for networks/storage (see questions above), do I have a method to regenerate these uuid values inside xml files?
Thanks in advance for any pointer. Gianluca
On Mon, Jul 20, 2009 at 10:45:56AM +0200, Gianluca Cecchi wrote:
Hello, is there any pointer about how to set up a cluster of Qemu/KVM hosts? I'm on F11 x86_64 for the hosts.
I was going to answer this in detail, but I'm not really an expert on this. You may be better off looking at http://ovirt.org/, which is an open source management tool designed precisely for looking after networks of virt hosts. It is based on libvirt, and they have looked at and solved many of the issues you raise.
Rich.
The question I keep bumping into is where are the cluster resource scripts for libvirt or kvm virtual machines. Migration is nice, but it doesn't do much good in the event a server decides to up and die instead of going down cleanly...
On Monday 20 July 2009 01:45:56 Gianluca Cecchi wrote:
Hello, is there any pointer about how to set up a cluster of Qemu/KVM hosts? I'm on F11 x86_64 for the hosts. I read requirements for KVM migration in general highlighted at http://www.linux-kvm.org/page/Migration but I keep having doubts, in particular regarding libvirt configuration in cluster environments... Some questions about libvirt configuration:
- /etc/libvirt/qemu/networks
do the files inside here be identical between hosts (default.xml and other custom configured network ones)? What are the uuid tags into the xml for? Do they have to be identical for clusters or do they have to be absolutely different for a sort of "identification" of host (as the term seems to suggest)? If I have guests that use virbr0 and use dhcp for their network config, and want two different qemu/kvm hosts able to migrate these guests between them, need to have same config or what?
- the same for storage configuration and other parameters.
Suppose I clone a pre-config F11 host configured with libvirt, and suppose I have to differentiate uuid for networks/storage (see questions above), do I have a method to regenerate these uuid values inside xml files?
Thanks in advance for any pointer. Gianluca
Fedora-virt mailing list Fedora-virt@redhat.com https://www.redhat.com/mailman/listinfo/fedora-virt
On Mon, Jul 20, 2009 at 11:18:25AM -0700, Dwight Hubbard wrote:
The question I keep bumping into is where are the cluster resource scripts for libvirt or kvm virtual machines. Migration is nice, but it doesn't do much good in the event a server decides to up and die instead of going down cleanly...
I guess the answer is that libvirt is just an abstraction layer above various hypervisors. We leave these higher level operations to management tools, of which there are several (eg. oVirt - see my previous email).
Rich.
On Mon, Jul 20, 2009 at 10:45:56AM +0200, Gianluca Cecchi wrote:
Hello, is there any pointer about how to set up a cluster of Qemu/KVM hosts? I'm on F11 x86_64 for the hosts. I read requirements for KVM migration in general highlighted at http://www.linux-kvm.org/page/Migration but I keep having doubts, in particular regarding libvirt configuration in cluster environments... Some questions about libvirt configuration:
- /etc/libvirt/qemu/networks
do the files inside here be identical between hosts (default.xml and other custom configured network ones)? What are the uuid tags into the xml for? Do they have to be identical for clusters or do they have to be absolutely different for a sort of "identification" of host (as the term seems to suggest)? If I have guests that use virbr0 and use dhcp for their network config, and want two different qemu/kvm hosts able to migrate these guests between them, need to have same config or what?
- the same for storage configuration and other parameters.
You can use rhcs or pacemaker for this and share the vm configuration via e.g. gfs. Cheers, -- Guido
I' using rhcs, but I'm trying to setup a sort of actve active config. Where I have also clvmd and where I can have for example some LVs of a clustered VG active as disks of some VMs hosted on one server, while other LVs of this VG represent disks hosted on another host. Also, as I have no SAN in my test env I'm using drbd 8.3.2 in dual primary mode...
Before starting with the cluster arch I had been done tests with Qemu/Kvm and virt-manager using a standalone host. Then without restarting from zero and deleting things, I transformed my local VG into a drbd based one and I cloned the initial host
So the question arised about uuid values inside xml files... and for example if they have to be the same for storage config and network config or not...
I would like not to use GFS, so that I don't add another layer impacting performance and complexity.... But your saying I can use GFS for config does implicitly mean same config files, also in active-active config? Gianluca
On Sat, Jul 25, 2009 at 3:17 AM, Guido Güntheragx@sigxcpu.org wrote:
On Mon, Jul 20, 2009 at 10:45:56AM +0200, Gianluca Cecchi wrote:
Hello, is there any pointer about how to set up a cluster of Qemu/KVM hosts? I'm on F11 x86_64 for the hosts. I read requirements for KVM migration in general highlighted at http://www.linux-kvm.org/page/Migration but I keep having doubts, in particular regarding libvirt configuration in cluster environments... Some questions about libvirt configuration:
- /etc/libvirt/qemu/networks
do the files inside here be identical between hosts (default.xml and other custom configured network ones)? What are the uuid tags into the xml for? Do they have to be identical for clusters or do they have to be absolutely different for a sort of "identification" of host (as the term seems to suggest)? If I have guests that use virbr0 and use dhcp for their network config, and want two different qemu/kvm hosts able to migrate these guests between them, need to have same config or what?
- the same for storage configuration and other parameters.
You can use rhcs or pacemaker for this and share the vm configuration via e.g. gfs. Cheers, -- Guido
On Sat, Jul 25, 2009 at 12:11:40PM +0200, Gianluca Cecchi wrote: [..snip..]
So the question arised about uuid values inside xml files... and for example if they have to be the same for storage config and network config or not...
In principle they don't have to be the same across hosts since you can identify the network by name and the volumes by their path but I prefer to keep them in sync (using shared nfs in my case).
I would like not to use GFS, so that I don't add another layer impacting performance and complexity....
Keeping the storge in LVM without filesystem should be fine.
But your saying I can use GFS for config does implicitly mean same config files, also in active-active config?
Yes sure. I share configs across hosts and reload libvirtd's configuration when adding new kvm vms so it picks up the new configuration. Hope that helps, -- Guido
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Dwight Hubbard -
Gianluca Cecchi -
Guido Günther -
Richard W.M. Jones