September 2015 - Users - libvirt List Archives

[libvirt-users] how to use {6FDE7547-1B65-48ae-B628-80BE62016026}\VIOSerialPort ?
by Jean-Pierre Ribeauville 16 Sep '15

16 Sep '15

Hi, When adding a channel device on a Win2008R2 Guest, I got this new thing within registry : Key Name: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\{6FDE7547-1B65-48ae-B628-80BE62016026}\VIOSerialPort\4&7e8053e&0&02 Class Name: <NO CLASS> Last Write Time: 9/16/2015 - 4:09 PM Value 0 Name: DeviceDesc Type: REG_SZ Data: vport0p2 Value 1 Name: Capabilities Type: REG_DWORD Data: 0xe6 Value 2 Name: UINumber Type: REG_DWORD Data: 0x2 Value 3 Name: ConfigFlags Type: REG_DWORD Data: 0 Value 4 Name: HardwareID Type: REG_MULTI_SZ Data: {6FDE7547-1B65-48ae-B628-80BE62016026}\VIOSerialPort Value 5 Name: CompatibleIDs Type: REG_MULTI_SZ Data: Value 6 Name: ContainerID Type: REG_SZ Data: {90e92d57-5573-11e5-9d8e-806e6f6e6963} Value 7 Name: LocationInformation Type: REG_SZ Data: RedHat VIOSerial Port Key Name: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\{6FDE7547-1B65-48ae-B628-80BE62016026}\VIOSerialPort\4&7e8053e&0&02\LogConf Class Name: <NO CLASS> Last Write Time: 9/16/2015 - 4:10 AM Key Name: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\{6FDE7547-1B65-48ae-B628-80BE62016026}\VIOSerialPort\4&7e8053e&0&02\Control Class Name: <NO CLASS> Last Write Time: 9/16/2015 - 4:09 PM How may I use theses infos to get/send datas to the host via this channel ? Thanks for help. Regards, J.P. Ribeauville P: +33.(0).1.47.17.27.87 Puteaux 3 Etage 5 Bureau 4 jpribeauville(a)axway.com<mailto:jpribeauville@axway.com> http://www.axway.com<http://www.axway.com/> P Pensez à l'environnement avant d'imprimer.

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[libvirt-users] cpu frequency
by Paul Apostolescu 16 Sep '15

16 Sep '15

Is it possible to set the CPU frequency exposed to the guest operating system for a kvm-enabled virtual machine ? The documentation does not mention anything about it. Thanks.

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[libvirt-users] VM in a VM on kvm/qemu
by Digimer 13 Sep '15

13 Sep '15

Hi all, For development reasons, I've setup a pair of VMs (host is Fedora 22) running EL6 as an HA cluster. On these two nodes, I host a 3rd VM (so Fedora 22 -> 2x EL 6.7 -> El 6.7). Currently, 'EL' == CentOS, but I can switch to RHEL proper if need be. To my happy surprise, it actually works! Of course, the two-deep EL6 guest is slow as molasses. I don't really care about making it usably fast because this setup is purely to dev/test the HA cluster VMs. That said, a minimal EL6 install currently takes about 2 hours. So testing deleting/creating guests is very slow. So my question is; Understanding it will never be good performance, is there anything I can do to make the VM-in-a-VM faster? I tried looking for docs on this, looking for ways to tune, CPU/BIOS options to set, etc, without much luck. Most google results are about vmware and other hypervisors. Any pointers/tips/clue-sticks will be much appreciated! -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education?

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[libvirt-users] Backup a VM (using live external snapshot and blockcommit)
by Jérôme 11 Sep '15

11 Sep '15

Hi. I'm following here a conversation that was initiated on Kashyap's website [1]. We have a server we use as a host for virtual machines using KVM (virt-manager used for VM creation) and we would like to setup VM backups. Basically, we're thinking of a backup schedule like "keep 7 daily and 4 weekly backups". We'd rather not shutdown the VM every day so live backups would be nice. I've been doing my best with documentation found on the Internet. It is likely that the path I chose was not the best, so feel free to tell me if I'm asking the wrong questions and I should be proceeding totally differently. AFAIU, backups can be done at filesystem level (using LVM) and at virtualization level (using libvirt). We chose the libvirt way. AFAIU, live backups using libvirt may be done thanks to blockcommit as explained here on the wiki [2]. -> Considering our use case, is this the recommended way? Assuming yes, here is the plan. I wrote a script that does # Create snapshot virsh snapshot-create-as --domain $VM_NAME snap --diskspec vda,file=$VM_DIR/"$VM_NAME"-snap.qcow2 --disk-only --atomic --no-metadata --quiesce # Copy frozen backing file cp $VM_DIR/"$VM_NAME".qcow2 $SNAP_FILEPATH # Blockcommit snapshot back into backing file virsh blockcommit $VM_NAME vda --active --pivot # Remove snapshot file rm $VM_DIR/"$VM_NAME"-snap.qcow2 Variables should be self-explanatory: - VM_DIR is the directory where the VM are stored - VM_NAME is the name of the VM, and its qcow2 file is called VM_NAME.qcow2 - SNAP_FILEPATH is the full path (including name) where the backup should be created Using this scheme, we only keep snapshots for the time of the VM file copy, which is less than a minute. The backing chain is at most 'back <- snap', and most of the time just 'back'. If something ever happens to the VM (human error while being logged as root, attack from the internet,...), we'll turn off the VM, replace its qcow2 file and turn it back on. I understand that this method only saves disk states, so the VM will be started as if it had been powered-off suddenly while running (not quite: thanks to the '--quiesce' option, at least the disks are in a sane state). Not perfect but better than nothing. Those backups are meant to be used only when all else failed, anyway, it's not daily use. -> Does this make sense? Am I missing a feature or even a different approach that would make things simpler or more secure? Am I using libvirt snapshots for what they're not meant to? -> Anything wrong about my snapshot-create-as and blockcommit command lines? May I remove the snapshot with only a rm command? Now, a few side questions, as I might have messed up with the VM I was experimenting with. I used the same command lines as described above, except I didn't pass the '--no-metadata' option. Once the backing file was copied, I deleted the snapshot qcow2 file and thought I was done with it, until I realized the snapshot was still listed by virsh snapshot-list. And I couldn't find a way to delete it. (For the record, I asked on serverfault about that [3].) Ultimately, I found the snapshot's .xml descriptor and deleted it (in fact, moved it) while libvirtd was down. Now, the snapshot is not listed anymore. -> Am I getting away with it? Are there still some traces about that snapshot? Is my VM in an unsafe state? Anything I should do about it? -> What would be the proper way of dropping an external snapshot that was created without the '--no-metadata' option, then blockcommitted? I understand libvirt doesn't do it yet. Thanks for any hint. I naively thought our use case was pretty usual, and I must admit I didn't think I'd have to dive into this complexity, which is why I'm thinking there might be a more "common" way... [1] http://kashyapc.com/2014/10/07/libvirt-blockcommit-shorten-disk-image-chain… [2] http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit [3] http://serverfault.com/questions/721216/delete-orphan-libvirt-snapshot -- Jérôme

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[libvirt-users] Transient VM Usage
by Mcburn 11 Sep '15

11 Sep '15

Hey at all, my Name is Jens-Uwe Sperling. Iám a young student in computer science. I want install a VM for testing at home. i had install a VM with virt-install and the default parameters. (Number cpu, mem etc.) After that i install my OS and configure it. Now i want work on this image in a transient way. So i can use the OS with the given config but every change i do from now should not change my image. I found three ways to do that: - Make a snapshot from my image and kill the snapshot after using. - Using the transient option in the xml file under disk. - Making a qcow2 image and run that. I test the last one but for that i must change my xml file to use the new image. A little bit better explained: i must detach the old disk and attach the new one. So my questions are: - Is the last one stable? - whats your experience with the option transient? - Is the performance when i snapshot the image okay? - Do you had make experience with transient images? Thank you very much P.S. Maybe when you dont understand a sentences ask me. I do my best to explain it better. Jens

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[libvirt-users] Monitoring passthrough(SR-IOV) interfaces
by Tashi Lu 10 Sep '15

10 Sep '15

Hi all, is it possible to monitor guest's interface's stat which uses SR-IOV virtual function? I don't know how qemu/libvirt implement monitoring, if functions like interfaceStats are implemented in the host, I think there's little chance to do this due to SR-IOV's nature, is it right? If i can't use libvirt to monitor SR-IOV interfaces, is there another way to do monitoring except putting agent in the guest OS? thx

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[libvirt-users] How to ifup nic automaticly after hotplug nic for lxc
by Jackie 09 Sep '15

09 Sep '15

Hi experts, When I hotplug nic into lxc, the nic in lxc seemed to be down status as following: 1224: vnet0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000 link/ether fa:16:3e:fc:e5:96 brd ff:ff:ff:ff:ff:ff It seems mechanism such as udev is needed here. But I found udev is not supported well in lxc. So how can I get a 'up' nic after hotplug into lxc ? Very appreciate for your help. Jackie

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Re: [libvirt-users] Windows Guest ports enumeration ..
by Jean-Pierre Ribeauville 08 Sep '15

08 Sep '15

Hi, I add the device in the .xml conf file using this way : <channel type='unix'> <source mode='bind' path='//var/lib/libvirt/qemu/omnivision_1.agent'/> <target type='virtio' name='omnivision_1.agent' state='disconnected'/> <alias name='channel1'/> <address type='virtio-serial' controller='0' bus='0' port='2'/> </channel> After the guest has been rebooted, I see that the diver VirtIO-Serial Driver is now installed . So far so good .... Then, I tried to have a look within the registry but no additional key here : HKLM\HARDWARE\DEVICEMAP\SERIALCOMM Is it the right way to proceed ? Or did I miss something ? Thanks for help. Regards, J.P. De : Jean-Pierre Ribeauville Envoyé : mardi 8 septembre 2015 13:02 À : 'libvirt-users(a)redhat.com' Objet : Windows Guest ports enumeration .. Hi, Within following page : http://www.linux-kvm.org/page/Virtio-serial_API it's mentioned a link to "GetDevidePath" . Unfortunately link seems to be broken. Is there another way to get infos on how to enumerate ports ( on Windows guest) in order to retrieve a channel device newly created on the guest by adding it on the .xml configuration file ? Thanks. Regards, J.P. Ribeauville P: +33.(0).1.47.17.27.87 Puteaux 3 Etage 5 Bureau 4 jpribeauville(a)axway.com<mailto:jpribeauville@axway.com> http://www.axway.com<http://www.axway.com/> P Pensez à l'environnement avant d'imprimer.

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[libvirt-users] Windows Guest ports enumeration ..
by Jean-Pierre Ribeauville 08 Sep '15

08 Sep '15

Hi, Within following page : http://www.linux-kvm.org/page/Virtio-serial_API it's mentioned a link to "GetDevidePath" . Unfortunately link seems to be broken. Is there another way to get infos on how to enumerate ports ( on Windows guest) in order to retrieve a channel device newly created on the guest by adding it on the .xml configuration file ? Thanks. Regards, J.P. Ribeauville P: +33.(0).1.47.17.27.87 Puteaux 3 Etage 5 Bureau 4 jpribeauville(a)axway.com<mailto:jpribeauville@axway.com> http://www.axway.com<http://www.axway.com/> P Pensez à l'environnement avant d'imprimer.

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[libvirt-users] Detecteion of a channel device on a Windows Guest
by Jean-Pierre Ribeauville 07 Sep '15

07 Sep '15

Hi Are there some docs/hint concerning following topic : - After adding a channel device in a Windows 2008 R2 guest .xml conf file : is there anything to do so this device appears "automagically " in the Windows Guest ? Thx. Regards, J.P. Ribeauville P: +33.(0).1.47.17.27.87 Puteaux 3 Etage 5 Bureau 4 jpribeauville(a)axway.com<mailto:jpribeauville@axway.com> http://www.axway.com<http://www.axway.com/> P Pensez à l'environnement avant d'imprimer.

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