Assigned CPUs Decreased and Guest Server Hangs

Question

Hi,
I created a physical virtual machine Oracle Enterprise Linux Server release 5.6 on Oracle VM server release 2.2.1. This is a DELL PowerEdge R710 with 2 4-cores Intel Xeon E5620 CPUs and 96GB memories. And the OLE is the only guest on the host. The first 12 virtual CPUs, 0-11, out of the 16 total available vcpu are assigned to the virtual machine and this configuration worked for more than 2 years.
The guest hang this morning. The number of the online vcpus dropped from 12 to 1 (used xm list to show the information) and the guest did not response at all. None of the ping, ssh, ftp or the applications on the server were OK. Though I connected to the console using a vncviewer client, the console was black at all. Nothing can be observed from the guest. The host is OK.
I connect to the host, destroied the guest (the connected vncviewer was disconnected automatically too), restarted it and it works as expected. The number of the online vcpus is 12 now.
The exactly same happened in April last year too.
I searched the Internet but could not find anything similar. Because I don't have a support of the virtual server, this is the only place I can think of for help.
Did anyone meet this before? Any suggestion on how to solve this problem, or how to find out the reason?
Regards,
Chiyuan

Answer 1

And the information of the guest is below.
[root@oravm ~]# xm list VMGuest -l
(domain
(domid 2)
(on_crash restart)
(uuid ac871ffe-887e-9934-7534-da476e364598)
(bootloader_args -q)
(vcpus 12)
(name VMGuest)
(on_poweroff destroy)
(on_reboot restart)
(cpus
((0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(0 1 2 3 4 5 6 7 8 9 10 11)
(bootloader /usr/bin/pygrub)
(maxmem 73728)
(memory 73728)
(shadow_memory 0)
(features )
(on_xend_start ignore)
(on_xend_stop ignore)
(start_time 1334703422.3)
(cpu_time 5142201.13696)
(online_vcpus 1)
(image
(linux
(kernel )
(superpages 0)
(videoram 4)
(device_model /usr/lib/xen/bin/qemu-dm)
(notes
(HV_START_LOW 0)
(FEATURES '!writable_page_tables|pae_pgdir_above_4gb')
(VIRT_BASE 2147483648)
(GUEST_VERSION 2.6)
(PADDR_OFFSET 0)
(GUEST_OS linux)
(HYPERCALL_PAGE 2164297728)
(LOADER generic)
(SUSPEND_CANCEL 1)
(PAE_MODE yes)
(ENTRY 2176119296)
(XEN_VERSION xen-3.0)
(status 2)
(state r-----)
(store_mfn 17639393)
(console_mfn 17639392)
(device
(vif
(bridge xenbr2)
(mac 00:16:3e:1b:66:ec)
(script /etc/xen/scripts/vif-bridge)
(uuid a2b74883-d709-123a-111d-d285cd87eb1d)
(backend 0)
(device
(vbd
(protocol x86_64-abi)
(uuid e8103d5b-0b30-89e5-8f0b-101d96d50558)
(bootable 1)
(dev xvda:disk)
(uname file:/OVS/running_pool/VMGuest/VMGuest_Root.dsk)
(mode w)
(backend 0)
(bootable 1)
(VDI )
(device
(vbd
(protocol x86_64-abi)
(uuid a4ef5167-0d28-ca9b-a6f2-66139215b687)
(bootable 0)
(dev xvdb2:disk)
(uname phy:/dev/sdb2)
(mode w)
(backend 0)
(bootable 0)
(VDI )
(device
(vbd
(protocol x86_64-abi)
(uuid f628699b-a06a-2372-5fba-48b3e5d11675)
(bootable 0)
(dev xvdc1:disk)
(uname phy:/dev/VmOS/VMGuest_Backup)
(mode w)
(backend 0)
(bootable 0)
(VDI )
(device (vkbd (backend 0)))
(device
(vfb
(vncunused 1)
(location 0.0.0.0:5900)
(vnc 1)
(xauthority /root/.Xauthority)
(uuid cd6fef1a-a380-f06b-130f-4de82844ea00)
(device
(console
(protocol vt100)
(location 2)
(uuid e587fb0e-a124-9770-d4ad-a08fb7fce68a)
)