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[libvirt-users] using vmchannel between 6.x host/guests
by Michael MacDonald 03 Jul '12

03 Jul '12

Hi all. Having trouble figuring out the magic to set up VMChannel comms between EL6.x host/guests. My end goal is to enable fence_virt in the guest to talk to fence_virtd on the host via VMChannel. I'd prefer to use that instead of multicast because it is supposed to work even if networking in the guest is down/borked. My analysis is that there is a mismatch between what libvirt is feeding qemu-kvm and what qemu-kvm is willing to accept: virt-install option: --channel unix,path=/var/run/cluster/fence/foobar,mode=bind,target_type=guestfwd,target_address=10.0.2.179:1229 turns into this XML: <channel type='unix'> <source mode='bind' path='/var/run/cluster/fence/foobar'/> <target type='guestfwd' address='10.0.2.179' port='1229'/> </channel> Which then gets fed to qemu-kvm as this: -chardev socket,id=charchannel0,path=/var/run/cluster/fence/foobar,server,nowait -netdev user,guestfwd=tcp:10.0.2.179:1229,chardev=charchannel0, id=user-channel0 And then qemu-kvm barfs like so: qemu-kvm: -netdev user,guestfwd=tcp:10.0.2.179:1229,chardev=charchannel0,id=user-channel0: Invalid parameter 'chardev' Versions: libvirt-0.9.10-21.el6.1 qemu-kvm-0.12.1.2-2.295.el6 NB: I did try this with the versions in 6.2, got the same result. Upgraded to these versions to see if the problem went away, but no joy. NB2: The fence_virt.conf manpage lists the following as example XML for defining a channel device: <channel type=’unix’> <source mode=’bind’ path=’/sandbox/guests/fence_molly_vmchannel’/> <target type=’guestfwd’ address=’10.0.2.179’ port=’1229’/> </serial> Any advice would be greatly appreciated. I can fall back to multicast, of course, but I'd like to make this work if possible. Thanks! Mike

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[libvirt-users] idle connections (?)
by Evaggelos Balaskas 02 Jul '12

02 Jul '12

Hello, i have noticed that for some reason my windows 2003 & windows 2008 VMs drops map drives caused by idle connections. I am not a windows admin and i have no knowledge of troubleshooting this, except reading support.microsoft.com The win admin is yelling that this is a fedora17 libvirt problem and that i need to fix this. I have two different net cards and i am using macvtap with vepa model for the VMs Is there any possibility that could be true ? Can i test somehow or prove that this is not related with libvirt ? Thanks in advance for any help. -- Evaggelos Balaskas - Unix System Engineer http://gr.linkedin.com/in/evaggelosbalaskas

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[libvirt-users] virsh iface-list () - function is not supported
by Ananth 02 Jul '12

02 Jul '12

Hi, I am using KVM hypervisor on Ubuntu 12.04 (libvirt-0.9.8). The call to list the interfaces seem to be failing on this version of libvirt as seen below. virsh # iface-list error: Failed to list active interfaces error: this function is not supported by the connection driver: virConnectNumOfInterfaces I have seen this issue with libvirt 0.9.2 as well, which seemed to be working in 0.9.4 version. Is there any work around for this or any alternate way of querying the interfaces and bridges through libvirt? -- Regards Ananth

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[libvirt-users] qemu-kvm fails on RHEL6
by sumit sengupta 02 Jul '12

02 Jul '12

Hi, When I'm trying to run qemu-kvm command on RHEL6(linux kernel 2.6.32) then I get following errors which I think related to tap devices in my setup. Any idea why is that? bash$ LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -S -M rhel6.2.0 -enable-kvm -m 512 -smp 1,sockets=1,cores=1,threads=1 -name instance-00000027 -uuid a93aeed9-15f7-4ded-b6b3-34c8d2c101a8 -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/instance-00000027.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -kernel /home/sumitsen/openstack/nova/instances/instance-00000027/kernel -initrd /home/sumitsen/openstack/nova/instances/instance-00000027/ramdisk -append root=/dev/vda console=ttyS0 -drive file=/home/sumitsen/openstack/nova/instances/instance-00000027/disk,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 -netdev tap,fd=26,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=fa:16:3e:15:84:3e,bus=pci.0,addr=0x3 -chardev file,id=charserial0,path=/home/sumitsen/openstack/nova/instances/instance-00000027/console.log -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -usb -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -k en-us -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 char device redirected to /dev/pts/1 qemu-kvm: -netdev tap,fd=26,id=hostnet0: TUNGETIFF ioctl() failed: Bad file descriptor TUNSETOFFLOAD ioctl() failed: Bad file descriptor qemu-kvm: -append root=/dev/vda: could not open disk image console=ttyS0: No such file or directory [sumitsen@sorrygate-dr ~]$ rpm -qa qemu-kvm qemu-kvm-0.12.1.2-2.209.el6.x86_64 Let me know if you need any other info. Thanks, Sumit

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[libvirt-users] How does libvirt interaction with KVM to create a VM?
by Dennis Chen 02 Jul '12

02 Jul '12

All, These days I am trying to understand the interaction relationship between the libvirt and KVM kernel module, eg. kvm_intel.ko. We know that KVM kernel module expose an entry in form of device file "/dev/kvm" which can be accessed by user space application to control, for example, create a VM using KVM_CREATE_VM with help of ioctl. Now let's say the tool virsh based upon libvirt, we can create a guest domain with the command looks like: #virsh create guest.xml Obviously, the above command will create a VM. But when I try to investigate the libvirt code, I can't find any code play with the "/dev/kvm" to send KVM_CREATE_VM ioctl code to KVM kernel module. But I do found that the reference count of the kvm_intel.ko changed before the virsh create command launched and after. So my question is: how does the libvirt interaction with KVM to create a VM? Anybody can give me some tips about that, eg, the corresponding codes in libvirt? BRs. Dennis

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[libvirt-users] (no subject)
by Daniele Milani 02 Jul '12

02 Jul '12

http://victorcoffa.nl/epoga.html?ffjk=idoinff

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[libvirt-users] Query:Creating a Guest that requires memory and vCPUs across socket boundary
by sanjay 30 Jun '12

30 Jun '12

Hi! If a KVM-QEMU guest (spawned using libvirt) requires memory and CPU cores that spans across socket boundaries and it wants to avoid memory access across NUMA nodes, what is the best way to proceed ? I came across the following statement during my search “If a guest requires eight virtual CPUs, as each NUMA node only has four physical CPUs, a better utilization may be obtained by running a pair of four virtual CPU guests and splitting the work between them, rather than using a single 8 CPU guest.” Is this statement still valid ? Can one use ‘numatune’ XML tag with ‘auto’ placement to create a guest, where vCPUs and memory is allocated in a efficient manner across sockets based on available memory? If one allocates memory across sockets and passes the topology information to Guest using 'numa' tag, will it help in avoiding the NUMA penalty (ex: <numa>/<cell cpus='0' memory=256000'><cell cpus='1' memory='512000') ? Any advise on this subject will be appreciated. -- Regards, Sanjay

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[libvirt-users] How to start a storage pool using libvirt?
by Ananth 29 Jun '12

29 Jun '12

Hi what is the libvirt API call to start an inactive storage pool created using the python binding storagePoolDefineXML() ? There seems to be a virsh command which is pool-start <pool-name>, but I am not sure what would be the call to start it. Or is there a way to start the pool while it is being defined itself? The autostart will be effective only when libvirtd service is restarted? Thank you -- Regards Ananth

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[libvirt-users] Storage Pools & nodedev-create specific scsi_host#?
by mdecheser＠comcast.net 29 Jun '12

29 Jun '12

Hello everyone, Current host build is RHEL 6.2, soon to be upgrading. I'm in the process of mapping out a KVM/RHEV topology. I have questions about the landscape of storage pools and the instantiation of specific scsi_host IDs using virsh nodedev-create and some magic XML definitions. I'm grouping these questions together because the answer to one may impact the other. High-level goals: - fence off I/O by providing NPIV paths to VMs individually - provide each VM with a pair of paths to the same storage for redundancy Problem 1 - Storage Pools: I've successfully created a storage pool by starting with an initial SCSI host based off one of my virtual HBAs. I see my LUNs. I performed a virsh pool-dumpxml and captured the configuration of the storage pool using just one SCSI host. I then modified the XML file to include a 2nd SCSI host, stopped & deleted the original storage pool, then created & started a new storage pool. In the GUI, I am able to see the same LUNs, listed twice (once for each path). Here's my XML file: <pool type='scsi'> <name>VM1POOL</name> <uuid>f0465f3f-3c9c-766c-3c96-678a99ec81cb</uuid> <capacity>144813588480</capacity> <allocation>144813588480</allocation> <available>0</available> <source> <adapter name='host5'/> </source> <source> <adapter name='host6'/> </source> <target> <path>/dev/disk/by-path</path> <permissions> <mode>0700</mode> <owner>-1</owner> <group>-1</group> </permissions> </target> </pool> Question 1 - Is this the correct approach for presenting a VM with SAN storage in a redundant fashion? Or should I instead use the mpath approach and find some way with the storage pool XML file to restrict which mpath devices are utilized (thereby restricting which LUNs the storage pool sees?). It seems my current approach provides each LUN twice, however a LUN has two different volume identifiers based on its path: UNIT:0:0:13 UNIT:0:1:13 Problem 2 - Specifying scsi_host# in a device XML file As I mentioned, I've successfully created a virtual HBA using virsh nodedev-create and an XML config. Here's a sample config: [root@host ~]# cat vm1vhba1.xml <device> <parent>scsi_host3</parent> <capability type='scsi_host'> <capability type='fc_host'> <wwnn>a97a3b9220010002</wwnn> <wwpn>a97a3b9220010001</wwpn> </capability> <capability type='vport_ops' /> </capability> </device> Pretty straightforward. The parent is physical SCSI host 3. The resulting SCSI host is 5. This is one of the SCSI hosts used in the storage pool above. So, I wanted to test what would happen to my VM if I ran virsh nodedev-destroy scsi_host5. Essentially, testing the redundancy of the paths to the VM. The device was successfully deleted, however a few other things happened, both expected and unexpected. - Since I only associated one of the two LUN units from my storage pool with the VM, I expected this to cause the VM to fail. It did fail, however in a headless fashion. Unexpected. The VM is still up and running in memory. Any effort to write out to the disks results in failures like "read-only filesystem". Expected. - The Storage Pool entered into an inactive state. Unexpected. Efforts to restart the storage pool using virsh pool-start failed because one of the scsi_host devices was not present. Expected. I tried to recreate the device using virsh nodedev-create vm1vhba1.xml, and the device was created successfully but as scsi_host9 (the next available scsi_host beyond the original scsi_host5). So, unless I can recreate this scsi_host5, I won't be able to restart my storage pool and restore I/O to my VM. Question 2: Is there a definition I can use in the XML config to specify the resulting scsi_host #? I've been told that RHEL 6.3 is supposed to provide some methodology of auto-instantiating my virtual HBAs upon the reboot of a host so that the VMs on the will see their storage and can start automatically on boot. I have a feeling that the answer to my question may be brushing up against this functionality. I am also assuming that if it's possible to specify the scsi_host# in my XML config, that I'll be able to restart my storage pool successfully and that will enable my VM to reestablish the connection to their storage. Thanks in advance, MD

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[libvirt-users] Speed of physical NIC?
by Marcel Müller 28 Jun '12

28 Jun '12

Hello everyone, Im trying to use libvirt to calculate some statistics about the current guest utilizations, but I do have some problems in regards of networking. I can do sampling of network speed by using the interfaceStats-API over a predefined period of time. But to calculate the percentage of the used bandwidth I need to know to what kind of network the interface is connected to 100 Mbit/s, 1000 Mbit/s, ? Is there any way to get this information through Libvirt or is there any addition planned for that? Thank you very much in advance, Best Regards, Marcel

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