On 01/25/2014 04:23 AM, Kewei Yu wrote:

Hi all:
     There is a "machine type" in cluster, It will decide which machine
of Qemu will be used, When we add the first host into cluster, a default
machine type is shown. We can correct the DB's value of the engine to
set the machine type.
     I just want to know how dose cluster choice the default machine? It
is decided by VDSM? Qemu? or It is only fixed value in engine's DB?

Regard
Kewei

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basically, for fedora its 'pc', which may have some live migration issues between different versions in the same cluster.
for .el6, its 'rhel63/rhel64/rhel65/etc.', which is a stable definition of emulation mode for the cluster (i.e., even a .el7 host should live migrate to .el6 if we specify its emulation mode as rhel65, etc.)

engine defines per cluster level the expected emulation mode.
vdsm reports from libvirt from qemu, so engine can check the host is a match.
if the first host in the cluster is fedora, it will be set to 'pc', if its .el6, it will be set to the 'rhelxx' option.