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[libvirt-users] inquiry about differences between the tap and the vnet in the virt-manager
by wh.h＠foxmail.com 21 Apr '15

21 Apr '15

inquiry about differences between the tap and the vnet in the virt-manager Greetings! I encounter a problem about the network when using virt-manager to create and run a VM. when I want to establish a network bridge for the guest OS, I generally use two kinds of ways described as fellow : First method : create a bridge with the help of linux commad: brctl, or Second method : using virt-manager (1) create a bridge with the help of linux commad: brctl I use a script to establish a bridge, there are many script examples on the web to establish a bridge. when I restart the network service, I get the bridge : 1.1 create network bridge [root@localhost ~]# ifconfig br0 Link encap:Ethernet HWaddr C2:CD:89:61:2C:F0 inet addr:192.168.1.189 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::c0cd:89ff:fe61:2cf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:1080 (1.0 KiB) eth2 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet addr:172.16.1.189 Bcast:172.16.255.255 Mask:255.255.0.0 inet6 addr: fe80::225:90ff:fe8e:c0f0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:918998 errors:0 dropped:0 overruns:0 frame:0 TX packets:2033 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:84486598 (80.5 MiB) TX bytes:148116 (144.6 KiB) Memory:fbe20000-fbe3ffff [root@localhost ~]# brctl show bridge name bridge id STP enabled interfaces br0 8000.0025908ec0f0 no virbr0 8000.525400b1de42 yes virbr0-nic 1.2 add bridge interface the eth2 device is a physical ethernet device, [root@localhost ~]# brctl addif br0 eth2 [root@localhost ~]# brctl show bridge name bridge id STP enabled interfaces br0 8000.0025908ec0f0 no eth2 virbr0 8000.525400b1de42 yes virbr0-nic 1.3 create tap and add it to the bridge create tap: tunctl -t tap0 -u root brctl addif br0 tap0 ifconfig tap0 up chmod a+rw /dev/net/tun echo 1 > /proc/sys/net/ipv4/ip_forward iptables -t nat -A POSTROUTING -j MASQUERADE add it to the bridge [root@localhost ~]# brctl addif br0 tap0 [root@localhost ~]# brctl show bridge name bridge id STP enabled interfaces br0 8000.0025908ec0f0 no eth2 tap0 virbr0 8000.525400b1de42 yes virbr0-nic [root@localhost kvm_img]# ifconfig br0 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet addr:172.16.1.189 Bcast:172.16.255.255 Mask:255.255.0.0 inet6 addr: fe80::c0cd:89ff:fe61:2cf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:37947 errors:0 dropped:0 overruns:0 frame:0 TX packets:10485 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2581300 (2.4 MiB) TX bytes:40996927 (39.0 MiB) eth2 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet6 addr: fe80::225:90ff:fe8e:c0f0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:957962 errors:0 dropped:34 overruns:0 frame:0 TX packets:38466 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:87721507 (83.6 MiB) TX bytes:42551007 (40.5 MiB) Memory:fbe20000-fbe3ffff tap0 Link encap:Ethernet HWaddr F2:55:FC:F8:95:DC inet6 addr: fe80::f055:fcff:fef8:95dc/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:11 errors:0 dropped:0 overruns:0 frame:0 TX packets:1328 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:846 (846.0 b) TX bytes:173159 (169.1 KiB) 1.4 boot the guest (using the tap0) kvm -boot c -localtime -m 4G -hda /home/kvm_img/centos6p4.img -net nic -net tap,ifname=tap0,script=no -enable-kvm (2) using virt-manager 2.1 create network bridge [root@localhost ~]# ifconfig br0 Link encap:Ethernet HWaddr C2:CD:89:61:2C:F0 inet addr:192.168.1.189 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::c0cd:89ff:fe61:2cf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:1080 (1.0 KiB) eth2 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet addr:172.16.1.189 Bcast:172.16.255.255 Mask:255.255.0.0 inet6 addr: fe80::225:90ff:fe8e:c0f0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:918998 errors:0 dropped:0 overruns:0 frame:0 TX packets:2033 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:84486598 (80.5 MiB) TX bytes:148116 (144.6 KiB) Memory:fbe20000-fbe3ffff [root@localhost ~]# brctl show bridge name bridge id STP enabled interfaces br0 8000.0025908ec0f0 no virbr0 8000.525400b1de42 yes virbr0-nic 2.2 add bridge interface the eth2 device is a physical ethernet device, [root@localhost ~]# brctl addif br0 eth2 [root@localhost ~]# brctl show bridge name bridge id STP enabled interfaces br0 8000.0025908ec0f0 no eth2 virbr0 8000.525400b1de42 yes virbr0-nic 2.3 run the virt-manager and select the NIC option I find the bridge created above , configure it as fellow : in "Virtual Network Interface " setting: Source device: Host device tap0 (bridge br0) Device model: e1000 Mac address: 52:54:00:84:E3:62 2.4 I start the VM using virt-manager I get a vnet0 device created by virt-manager, [root@localhost ~]# ifconfig br0 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet addr:172.16.1.189 Bcast:172.16.255.255 Mask:255.255.0.0 inet6 addr: fe80::c0cd:89ff:fe61:2cf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:62160 errors:0 dropped:1 overruns:0 frame:0 TX packets:22071 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:4007196 (3.8 MiB) TX bytes:59626981 (56.8 MiB) eth2 Link encap:Ethernet HWaddr 00:25:90:8E:C0:F0 inet6 addr: fe80::225:90ff:fe8e:c0f0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:982209 errors:0 dropped:47 overruns:0 frame:0 TX packets:61101 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:89496644 (85.3 MiB) TX bytes:61778801 (58.9 MiB) Memory:fbe20000-fbe3ffff vnet0 Link encap:Ethernet HWaddr FE:54:00:84:E3:62 inet6 addr: fe80::fc54:ff:fe84:e362/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5 errors:0 dropped:0 overruns:0 frame:0 TX packets:114 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:670 (670.0 b) TX bytes:13720 (13.3 KiB) both of the methods above seems that the network of guest OS is OK at most of environments, and I can get the attributes of the virtual network device . They are seemed to be the same. about the tap0： [root@localhost ~]# ethtool -i tap0 driver: tun version: 1.6 firmware-version: bus-info: tap supports-statistics: no supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no about the vnet0 created by virt-manager : [root@localhost ~]# ethtool -i vnet0 driver: tun version: 1.6 firmware-version: bus-info: tap supports-statistics: no supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no but the action between tap and vnet is not exactly the same！I will describe it in the following. this is my project environment: hardware : intel xeon E5 2600 server from supermicro host OS: centos 6.4 (kernel version is changed to 3.15.10 by me) virtual software : KVM+qemu 2.1.3 guest OS: centos 6.4 (kernel is not changed : 2.6.32 64bit) when I establish the network by the first method: create a bridge with the help of Linux commad: brctl, tap0 device is created in the host and assigned to the guest OS. tap0 device gets a name “eth0” in the guest OS. I use “ping ” command to test network state . I get the following result : concept explanation : local host: the OS where the guest OS is running remote host: another server which is connected to the local host using ethernet network . and this is my results: ping local host from guest OS is OK, I get reply from local host; ping remote host from local host is OK, I get reply from remote host; ping remote host from guest OS is not OK, I don’t get any reply from remote host; and this is my question. when I establish the network by the second method: using virt-manager, at this time , vnet0 device is created in the host and assigned to the guest OS. vnet0 device gets a name “eth0” in the guest OS. I also use “ping ” command to test network state . I get the following result : ping local host from guest OS is OK, I get reply from local host; ping remote host from local host is OK, I get reply from remote host; ping remote host from guest OS is OK, I get reply from remote host; my question is : why I cannot get reply when I ping remote host from guest OS using the first method? I use the same bridge: br0, so I think that the bridge: br0 is not responsible for the fault. and I have also stop the firewall . I guess the reason is that there are some differences between the tap device created by linux command and vnet device created by virt-manager. could you please kindly give my some advices to solve the problem ? I would be grateful if you could give me some advice . look forward to your reply ! weihua wh.h(a)foxmail.com

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[libvirt-users] Question regarding management of VMs using libvirtd.
by somenathpal . 21 Apr '15

21 Apr '15

Hi All, I have a question regarding the uses of libvirtd. We have the following situation to manage. We have several hosts with libvirtd running. We have one management application to manage different VMs launched in those different hosts. We want to configure the system such a way so that one libvirtd can collect information about the VMs launched by other libvirtd running in different hosts. Is it possible? Could you please point me to some resource around this? In this we will be able to get information about VMs from single source and need not to query different host for VMs info. Regards, Somenath

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[libvirt-users] virsh shutdown <domain> not fully working on win7 ?
by Marko Weber | 8000 21 Apr '15

21 Apr '15

hello list, i have a running vm with win7. When i fire up an 'virsh shutdown win7' nothing happens. When i fire up a second the same command, then the win7 machine is shutting down. Why do i need to fire up this command twice? Any ideas? best regards marko --

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[libvirt-users] (no subject)
by Daniel Sanabria 19 Apr '15

19 Apr '15

Hi, After upgrading my systems to Fedora 21 I decided to give Firewalld and NetworkManager technologies a try instead of keep relying on iptables and network.service but I now have my doubts. I have a F21 host with br0 configured with a network-script file to obtain its IP via dhcp (no problems with this), firewalld is running on the host and the guests are using br0 and dhcp to obtain the IPs from the same source the host/br0 is getting its own IP. The problem I'm having is that, after some time, packets from the guests are not being forwarded by br0 but I can't quite locate the reason for this. It is not until I restart the guest that everything starts working again (restarting NetworkManager in the guest does not work). Why br0 stops forwarding packets? What would be the right approach to get this setup working? Should I just forget about Firewalld and NetworkManager by disable them and instead keep using iptables and network.service? Thanks in advance, Daniel

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[libvirt-users] virsh shutdown <domain> not fully working on win7 ?
by Marko Weber | 8000 17 Apr '15

17 Apr '15

hello list, i have a running vm with win7. When i fire up an 'virsh shutdown win7' nothing happens. When i fire up a second the same command, then the win7 machine is shutting down. Why do i need to fire up this command twice? Any ideas? best regards marko --

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[libvirt-users] New application, which uses libvirt
by Maciej Nabożny 17 Apr '15

17 Apr '15

Hello, a couple years ago, I've asked you to add the Cracow Cloud One project to application list (http://libvirt.org/apps.html) For over one year I'm developing new IaaS cloud, based on that application, which is its fork. Would it be possible to add this new project to Libvirt application list? CloudOver - elastic and modular IaaS cloud designed to run in small environments, like computer labs and offices. Provides graphical web interface and simple python bindings to manage all resources. Additional plugins make easy to extend its core functionality. Regards, Maciej Nabożny

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[libvirt-users] unknown driver format value 'qcow3'
by Jatin Davey 16 Apr '15

16 Apr '15

Hi All I am trying to deploy VMs using libvirt and a domainXML file where i mention the parameters for the VM to be deployed. I am using libvirt version: libvirt 0.10.2 ********** virsh # version Compiled against library: libvirt 0.10.2 Using library: libvirt 0.10.2 Using API: QEMU 0.10.2 Running hypervisor: QEMU 0.12.1 *********** I get this libvirt exception while deploying a VM. Exception trace ************** 2015-04-14 18:06:28,240 [pool-1-thread-45] ERROR defineDomain(SimpleAppliance.java:581) - Failed to define domain/VM from XML org.libvirt.LibvirtException: unsupported configuration: unknown driver format value 'qcow3' at org.libvirt.ErrorHandler.processError(Unknown Source) at org.libvirt.Connect.processError(Unknown Source) at org.libvirt.Connect.processError(Unknown Source) at org.libvirt.Connect.domainDefineXML(Unknown Source) ******************************** Do i need to upgrade to any specific version of libvirt ? or change any file to make this work ? Thanks Jatin

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[libvirt-users] VM Performance using KVM Vs. VMware ESXi
by Jatin Davey 15 Apr '15

15 Apr '15

Hi All We are currently testing our product using KVM as the hypervisor. We are not using KVM as a bare-metal hypervisor. We use it on top of a RHEL installation. So basically RHEL acts as our host and using KVM we deploy guests on this system. We have all along tested and shipped our application image for VMware ESXi installations , So this it the first time we are trying our application image on a KVM hypervisor. On this front i have done some tests to find out how our application's response time is when deployed on KVM and then compare it with a VM deployed on VMware ESXi. We have a benchmark test that basically loads the application simulating a load of 100 parallel users logging into the system and downloading reports. These tests basically use a HTTP GET query to load the application VM. In addition to that i have taken care to use the same hardware for both the tests , one with RHEL(Host)+KVM and another with VMware ESXi. All the hardware specifications for both the servers remain the same. The load test also remains the same for testing with both the servers. First observation is that the average response time on the VMware ESXi is : 500 milli-seconds while the application's average response time when deployed using RHEL(Host)+ KVM is : 1050 milli-seconds. The response time of the application when deployed on KVM is twice as much as when it is deployed using VMware ESXi. I did few more tests to find which sub-system on these servers shows varying metrics. First i started with IOZone to find out if there is any mismatch in the speed with which data is read / written to the local disk on the two VMs and found that "Read" speed in the VM that was deployed using RHEL(Host)+KVM was twice as slow as the VM which was deployed using VMware ESXi. For more on IoZone , Please refer : http://www.iozone.org/ more specifically the following IoZone metrics were twice as less when compared to the server running with VMware ESXi: Read Re-read Reverse-Read Stride Read Pread Note: I had run the IoZone tests on the VMs on both the servers. Second observation to be made was the output from the "top" command. I could see that the VM deployed on RHEL(Host)+KVM was showing high numbers for the following metrics when compared with the VM deployed on VMware ESXi: load averages %sy for all the logical processors %si for all the logical processors i debugged further to find out which device is causing more interrupts and found it to be "ide0" , See the output from the /proc/interrupts file below: The other interrupts apart from ide0 are pretty much similar to the VM deployed using VMware ESXi. ************/proc/interrupts ******************* [root@localhost ~]# cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7 0: 795827 0 0 0 0 0 0 0 IO-APIC-edge timer 1: 65 0 0 0 0 0 0 0 IO-APIC-edge i8042 6: 2 0 0 0 0 0 0 0 IO-APIC-edge floppy 8: 0 0 0 0 0 0 0 0 IO-APIC-edge rtc 9: 0 0 0 0 0 0 0 0 IO-APIC-level acpi 10: 425785 0 0 0 0 0 0 0 IO-APIC-level virtio0, eth0 11: 47 0 0 0 0 0 0 0 IO-APIC-level uhci_hcd:usb1, HDA Intel 12: 730 0 0 0 0 0 0 0 IO-APIC-edge i8042 14: 188086 0 0 0 0 0 0 0 IO-APIC-edge ide0 NMI: 0 0 0 0 0 0 0 0 LOC: 795813 795798 795783 795767 795752 795737 795723 795709 ERR: 0 MIS: 0 ********************************************* Any pointers to improving the response time for the VM for RHEL(Host)+KVM installation would be greatly appreciated. Thanks Jatin

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[libvirt-users] oddity with lxc-enter-namespace
by Thierry Parmentelat 15 Apr '15

15 Apr '15

Hi folks I have a question about lxc-enter-namespace I am migrating lxc containers from a host running libvirt-1.2.5 on f20 to another one running libvirt-1.2.9 on f21 and now I can't seem to use lxc-enter-namespace for entering in a container any more I would do virsh -c lxc:/// lxc-enter-namespace --noseclabel container /bin/bash but when I try the same now I am getting this: # virsh -c lxc:/// lxc-enter-namespace --noseclabel nagios /bin/bash setlocale: No such file or directory libvirt: error : Expected at least one file descriptor error: internal error: Child process (137198) unexpected exit status 125 I tried to google that but nothing too relevant showed up.. are there known regressions to lxc-enter-namespace, or what else do I seem to do wrong here? thanks

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[libvirt-users] One issue for help, Thanks
by Guozhonghua 15 Apr '15

15 Apr '15

Hi, All As we execute the virsh command and get the return code in my shell script, the code is 141. virsh blockcommit $VM_NAME --path $vm_data_file --base $backing_file --wait rtn_code=$? We get the return code with 141 in script accidentally. And most time we get the code with zero or one. We don't know the reason that the command "virsh blockcommit" return with 141(May be 128 + 13(SIGPIPE)). We refer to http://unix.stackexchange.com/questions/99112/default-exit-code-when-proces…. Can we change some code of libvirt to avoid the 141 code? Thanks. ------------------------------------------------------------------------------------------------------------------------------------- ???????????????????????????????????????? ???????????????????????????????????????? ???????????????????????????????????????? ??? This e-mail and its attachments contain confidential information from H3C, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it!

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