Hello,

my suspect was correct.

I found some reference here about possible values:

http://www.ovirt.org/Features/Detailed_NUMA_and_Virtual_NUMA

so I made this

[root@ovirtmgr ~]# cat numa_tune.xml

<vm><numa_tune_mode>interleave</numa_tune_mode></vm>

[root@ovirtmgr ~]# curl --insecure -u "admin@internal:my_password" -H "Content-type: application/xml" -T numa_tune.xml 'https://ovirtmgr/api/vms/168470b1-b7eb-4dab-8fa4-6b744e2ad738'

and now start of VM succeeds with

[root@ovirtmgr ~]# curl --insecure --request POST -H "Content-type: application/xml" -u "admin@internal:my_password" --header "Accept: application/xml" --data '<action> </action>' "https://ovirtmgr/ovirt-engine/api/vms/168470b1-b7eb-4dab-8fa4-6b744e2ad738/start"

In qemu log file for the VM

2014-09-25 13:55:38.111+0000: starting up

LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin QEMU_AUDIO_DRV=spice /usr/libexec/qemu-kvm -name ubuntutrusty -S -M rhel6.5.0 -cpu Nehalem -enable-kvm -m 4096 -realtime mlock=off -smp 1,maxcpus=16,sockets=16,cores=1,threads=1 -uuid 168470b1-b7eb-4dab-8fa4-6b744e2ad738 -smbios type=1,manufacturer=oVirt,product=oVirt Node,version=6-5.el6.centos.11.2,serial=9B1B2F84-3CB9-11DE-B5A1-001517B493E8,uuid=168470b1-b7eb-4dab-8fa4-6b744e2ad738 -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/ubuntutrusty.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=2014-09-25T15:55:37,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x5 -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x6 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw,serial= -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -drive file=/rhev/data-center/4512e567-f94e-476a-a050-6cd0a15e260a/346732c8-e1e9-49de-9ca4-63f4477ef6dd/images/d690177e-eca6-4dd2-9380-9d2d49c35b68/cc46a780-ea50-4a71-8acc-963f703e7321,if=none,id=drive-virtio-disk0,format=qcow2,serial=d690177e-eca6-4dd2-9380-9d2d49c35b68,cache=none,werror=stop,rerror=stop,aio=native -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=25,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:01:a4:a3:42:02,bus=pci.0,addr=0x3 -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channels/168470b1-b7eb-4dab-8fa4-6b744e2ad738.com.redhat.rhevm.vdsm,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm -chardev socket,id=charchannel1,path=/var/lib/libvirt/qemu/channels/168470b1-b7eb-4dab-8fa4-6b744e2ad738.org.qemu.guest_agent.0,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=org.qemu.guest_agent.0 -chardev spicevmc,id=charchannel2,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=3,chardev=charchannel2,id=channel2,name=com.redhat.spice.0 -spice port=5900,tls-port=5901,addr=192.168.1.74,x509-dir=/etc/pki/vdsm/libvirt-spice,tls-channel=main,tls-channel=display,tls-channel=inputs,tls-channel=cursor,tls-channel=playback,tls-channel=record,tls-channel=smartcard,tls-channel=usbredir,seamless-migration=on -k en-us -vga qxl -global qxl-vga.ram_size=67108864 -global qxl-vga.vram_size=33554432 -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8

The question now is how can I influence configuration from the GUI so that all my VMs are by default created as interleave.

I will also try to create VM from scratch in 3.5rc3 to find if the problem could arise only for pre-existing VMs or not...

Comments welcome on my findings....

Gianluca