April 2015 - Users - libvirt List Archives

[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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[libvirt-users] Update on-disk XML after virsh snapshot-create-as
by Andrew Martin 14 Apr '15

14 Apr '15

Hello, I am using "virsh snapshot-create-as" to create external snapshots of running VMs using libvirt 1.0.2 on Ubuntu 12.04 and libvirt 1.2.2 on Ubuntu 14.04. This works well for creating the snapshots, but I notice that the on-disk XML file in /etc/libvirt/qemu is not updated with the new disk image file after the snapshot is created. This appears to be very similar to https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1403841, but occurs on both 12.04 and 14.04 so I am not sure it is the same bug. This presents a problem if the virtual machine host is suddenly powered off since a subsequent boot will find the VM using an older image file to boot rather than the most recent snapshot. Is it safe for me to use an external wrapper script that does the following to ensure the on-disk XML is up-to-date: virsh snapshot-create-as .... virsh dumpxml > /etc/libvirt/qemu/<domain>.xml Is it safe for me to overwrite the contents of /etc/libvirt/qemu/<domain>.xml manually while the VM is running? Thanks, Andrew Martin

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[libvirt-users] How to burn a CD using libvirt?
by Steve Ross 14 Apr '15

14 Apr '15

Hi, My first e-mail... my apologies if this is not the appropriate e-mail list. My goal is to *write* from the guest OS to a CD or DVD reader/writer on my host system. Currently, the write operation is failing. I believe it is because the virtual CD-ROM device is set to be "readonly". Is it possible to write to a QEMU CDROM device and, if so, how? (The host machine's CD-ROM drive does support writing/burning.) I'm using the "virt-manager" GUI to start the virtual machine. Once started, the "qemu" command line from my virtual machine process includes the following, where the host's built-in CD reader/writer is "/dev/sr0". /usr/bin/qemu-system-x86_64 ... -drive file=/dev/sr0,if=none,id=drive-ide0-0-1,readonly=on,format=raw This obviously says that the device is "readonly". A snippet of XML from my virtual machine from the CDROM is: <domain type='kvm'> ... <devices> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <source dev='/dev/sr0'/> <target dev='hdb' bus='ide'/> <readonly/> <address type='drive' controller='0' bus='0' target='0' unit='1'/> </disk> I've tried removing the <readonly/> tag from the above VM definition, and then running the VM, but the tag magically reappears in the VM definition when it runs. Also, the "virt-manager" GUI shows the CDROM device as having the option of "Readonly" being checked (and the GUI does not allow me to uncheck it.) Other details: * qemu version 2.1.3 on Fedora 21. * libvirt version 1.2.0.2 Thanks for any help or pointers you can provide, -- Steve

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[libvirt-users] XML Parser failing due to cryptic Serial Number.
by Roz Fx 14 Apr '15

14 Apr '15

I set virt-manager in qemu:///system space and tried to add new VM but it didn't proceed. Found out serial in crypic form. # cat /sys/devices/virtual/dmi/id/product_serial ÿÿÿÿÿÿÿ #virt-manager --debugTraceback (most recent call last): File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 225, in _reparse_xml self._xmlobj = self._build_xmlobj(self._get_raw_xml()) File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 228, in _build_xmlobj return self._parseclass(self.conn.get_backend(), parsexml=xml) File "/usr/share/virt-manager/virtManager/nodedev.py", line 27, in _parse_convert return NodeDevice.parse(conn, parsexml) File "/usr/share/virt-manager/virtinst/nodedev.py", line 95, in parse tmpdev = NodeDevice(conn, parsexml=xml, allow_node_instantiate=True) File "/usr/share/virt-manager/virtinst/nodedev.py", line 106, in __init__ XMLBuilder.__init__(self, *args, **kwargs) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 777, in __init__ parent_xpath, relative_object_xpath) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 679, in __init__ self._parse(parsexml, parsexmlnode) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 692, in _parse doc = libxml2.parseDoc(xml) File "/usr/lib/python2.7/site-packages/libxml2.py", line 1327, in parseDoc if ret is None:raise parserError('xmlParseDoc() failed') libxml2.parserError: xmlParseDoc() failed [Sun, 12 Apr 2015 06:06:16 virt-manager 4241] DEBUG (create:165) Showing new vm wizard [Sun, 12 Apr 2015 06:06:16 virt-manager 4241] DEBUG (create:892) Guest type set to os_type=hvm, arch=x86_64, dom_type=kvm [Sun, 12 Apr 2015 06:06:16 virt-manager 4241] DEBUG (xmlbuilder:694) Error parsing xml= <device> <name>computer</name> <capability type='system'> <product>Vostro</product> <hardware> <vendor>Dell Inc.</vendor> <version>A10</version> <serial>ÿÿÿÿÿÿÿ</serial> <uuid>REMOVED</uuid> </hardware> <firmware> <vendor>Dell Inc.</vendor> <version>A10</version> <release_date>05/18/2013</release_date> </firmware> </capability> </device> [Sun, 12 Apr 2015 06:06:16 virt-manager 4241] ERROR (create:346) Error setting create wizard conn state. Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/create.py", line 344, in reset_state self.set_conn(activeconn, force_validate=True) File "/usr/share/virt-manager/virtManager/create.py", line 225, in set_conn self.set_conn_state() File "/usr/share/virt-manager/virtManager/create.py", line 626, in set_conn_state self.netlist.reset_state() File "/usr/share/virt-manager/virtManager/netlist.py", line 405, in reset_state self._populate_network_list() File "/usr/share/virt-manager/virtManager/netlist.py", line 253, in _populate_network_list vnet_bridges) File "/usr/share/virt-manager/virtManager/netlist.py", line 185, in _find_physical_devices for nodedev in self.conn.get_nodedevs("net"): File "/usr/share/virt-manager/virtManager/connection.py", line 648, in get_nodedevs xmlobj = dev.get_xmlobj() File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 160, in get_xmlobj self._reparse_xml() File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 225, in _reparse_xml self._xmlobj = self._build_xmlobj(self._get_raw_xml()) File "/usr/share/virt-manager/virtManager/libvirtobject.py", line 228, in _build_xmlobj return self._parseclass(self.conn.get_backend(), parsexml=xml) File "/usr/share/virt-manager/virtManager/nodedev.py", line 27, in _parse_convert return NodeDevice.parse(conn, parsexml) File "/usr/share/virt-manager/virtinst/nodedev.py", line 95, in parse tmpdev = NodeDevice(conn, parsexml=xml, allow_node_instantiate=True) File "/usr/share/virt-manager/virtinst/nodedev.py", line 106, in __init__ XMLBuilder.__init__(self, *args, **kwargs) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 777, in __init__ parent_xpath, relative_object_xpath) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 679, in __init__ self._parse(parsexml, parsexmlnode) File "/usr/share/virt-manager/virtinst/xmlbuilder.py", line 692, in _parse doc = libxml2.parseDoc(xml) File "/usr/lib/python2.7/site-packages/libxml2.py", line 1327, in parseDoc if ret is None:raise parserError('xmlParseDoc() failed') parserError: xmlParseDoc() failed Any help will appreciate. RegardsRox

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[libvirt-users] libvirt vs PCI virtio
by Pavel Fedin 14 Apr '15

14 Apr '15

Hello! I am working on vhost-net support for ARM and want to try to set up complete configuration with irqfds. For this purpose i need to change address type specification for this device from "virtio-mmio" to "PCI". But, when i attempt to do so, i get error message "No PCI buses available". Can anybody explain me what i am doing wrong ? The most confusing part is that i use 'virt' machine which actually has generic PCI host, and for test purposes i even set up SATA controller for my virtual machine which perfectly appears on the emulated bus. And specification for SATA is simply: --- cut --- <controller type='sata' index='0'/> --- cut --- without any explicit PCI location specifiers. Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia

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[libvirt-users] Installing virtio drivers on a windows guest
by Jeff Tchang 14 Apr '15

14 Apr '15

Just thought I would share my experience trying to get the virtio windows drivers loaded. I kept using the wrong ones and getting a blue screen until I realized I needed to use my distribution's virtio packages. Wrote up a quick article: http://www.returnbooleantrue.com/2015/04/making-your-windows-kvm-guest-boxe…

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[libvirt-users] Passing environment variables to LXC container
by Harish Vishwanath 13 Apr '15

13 Apr '15

Hello I am looking for options to pass some ENV variables to an LXC container managed by libvirt. Is it possible to do so from the XML file itself? Something along the lines of qemu command line options? Regards, Harish

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[libvirt-users] CPU Resource Reservation using KVM
by Jatin Davey 13 Apr '15

13 Apr '15

Hi All I am new to KVM world. I have been using VMware for about a year. In VMware world we can reserve cpu resources for a VM. Say for instance if we need 4 vCPUs with a total of 8000 GHz then we can mention this configuration in vCenter while creating a VM. This guarantees 8000 GHz of cpu resources for the deployed VM. How can i achieve the same thing using KVM ? Please provide as much details as possible. Any pointers for reading this would also be helpful. Appreciate your responses in this regard. Thanks Jatin

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