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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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[libvirt-users] When adding a channel device, we need a shutdown
by Jean-Pierre Ribeauville 07 Sep '15

07 Sep '15

Hi, It looks like , when adding a channel device, that the Guest must be powered off / on to be able to detect the new device . ( simple reboot isn't not enough) Is there any way to avoid this power_cycle ? Thx. 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] Can't get PCI passthrough working
by Phill Edwards 06 Sep '15

06 Sep '15

I'm trying to get PCI passthrough working by passing through a DVB-T TV card to a VM running MythTV. When I assign the PCI devices in virt-manager and attempt to start the VM I get this error: Error starting domain: internal error: process exited while connecting to monitor: 2015-09-06T12:41:09.725990Z qemu-kvm: -device vfio-pci,host=05:02.0,id=hostdev0,bus=pci.0,addr=0x9: vfio: error, group 11 is not viable, please ensure all devices within the iommu_group are bound to their vfio bus driver. 2015-09-06T12:41:09.726034Z qemu-kvm: -device vfio-pci,host=05:02.0,id=hostdev0,bus=pci.0,addr=0x9: vfio: failed to get group 11 2015-09-06T12:41:09.726049Z qemu-kvm: -device vfio-pci,host=05:02.0,id=hostdev0,bus=pci.0,addr=0x9: Device initialization failed. 2015-09-06T12:41:09.726064Z qemu-kvm: -device vfio-pci,host=05:02.0,id=hostdev0,bus=pci.0,addr=0x9: Device 'vfio-pci' could not be initialized I've followed a whole load of instructions and made teh settings below: - Updated /etc/sysconfig/grub tp add intel_iommu=on: GRUB_CMDLINE_LINUX="rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet intel_iommu=on" - Allowed unsafe interrupts in /etc/modprobe.d/PME-vfio_iommu_type1.conf: options vfio_iommu_type1 allow_unsafe_interrupts=1 - Blacklisted the PCI card's drivers in /etc/modprobe.d/blacklist.conf so they don't get grabbed by the CentOS hypervisor host: blacklist cx8800 blacklist cx8802 blacklist cx88_dvb blacklist cx88-mpeg Can anyone please advise why I'm getting that error preventing the VM from booting?

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[libvirt-users] Can't get cable connection working on virtual router machine
by Phill Edwards 05 Sep '15

05 Sep '15

I'm pretty new to KVM and have a KVM CentOS 7.1 hypervisor running a few VMs. I'm moving all my VMs from an ESXi host as I want to use KVM in future. Most of my VMs are working except for one which is running a Sophos UTM router (Sophos UTM is similar to products like pfSense <https://www.pfsense.org/>, Smoothwall <http://www.smoothwall.org/> etc). The host has 3 physical NICs which are configured on the Sophos VM as: 1) LAN (fixed IP) 2) DMZ (fixed IP) 3) WAN (which is directly plugged into a cable modem for the internet connection and is configured DHCP). I have imported the settings from the "old" Sophos machine so I know the configuration of the new one is identical to the old one. I have even tried configuring the NICs to have the same MAC addresses as the old one. The problem is that no matter what I try I cannot get the WAN NIC to get an internet link up and running with my cable modem. I have re-installed the VM countless times, turned off the modem and VM, done a factory reset of the modem, and, as I mentioned, ensured the MAC addresses are the same. Nothing I try has been successful. The network interfaces on the new Sophos VM look like this: 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:79:d4:de brd ff:ff:ff:ff:ff:ff inet 192.168.0.254/24 brd 192.168.0.255 scope global eth0 valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1472 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:79:d4:e8 brd ff:ff:ff:ff:ff:ff 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:79:d4:f2 brd ff:ff:ff:ff:ff:ff inet 192.168.1.254/24 brd 192.168.1.255 scope global eth2 valid_lft forever preferred_lft forever I also found this in the /var/log/system.log of the Sophos VM: 2015:08:29-12:04:05 sop dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 6 2015:08:29-12:04:11 sop dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 13 2015:08:29-12:04:24 sop dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 2 2015:08:29-12:04:26 sop dhclient: No DHCPOFFERS received. I have shut down firewalld on the KVM host so I don't think there are any firewall rules blocking this. As soon as I fire up the original Sophos VM on ESXi the internet connection works perfectly again. If I can't get this VM running on KVM it's a show-stopper. Can anyone suggest what might be going on that is preventing the WAN link from connecting? Or suggest a way of troubleshooting this? Thanks in advance.

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