QEMU stands for "Quick EMUlator" and is a processor emulator that relies on dynamic binary translation to achieve a reasonable speed while being easy to port to new host CPU architectures.

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QEMU USB passthrough is not working

I stuck at getting USB passthrough working with Windows 8.1 guest OS on Ubuntu Server 14.04. I started by installing qemu using the Ubuntu Documentation (https://help.ubuntu.com/community/KVM). The ...
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15 views

kvm/qemu host windows guest BSOD about driver_irql_not_less_or_equal for viostore.sys

I have a KVM/Qemu host running 4 Windows Server 2012 guests and after upgrading the host from Ubuntu 12.04 to 14.04 I get blue screens with a bug check string of "driver_irql_not_less_or_equal" that ...
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1answer
12 views

enable vnc after virt-install

I've created a virtual machine using virt-install with graphics --none. I want to enable vnc. I've tried virsh -c qemu:///system qemu-monitor-command vm171-SC-1 --hmp change vnc :3 but it doesn't ...
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2answers
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Difference between KVM and QEMU

I have been reading about KVM and Qemu for sometime. As of now I have a clear understanding of what they do. KVM supports hardware virtualization to provide near native performance to the Guest ...
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1answer
1k views

How to fix a frozen qemu VM?

I have a qemu hypervisor on RHEL 6.4 that hosts VMs that will quite often lose their connection to the network. When the VM has lost its connection I can view and interact with the it using ...
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1answer
1k views

setting CPU cache size and model for KVM guest

Is there any possibility to create a custom CPU model for KVM Linux guests, or at least to modify parameters such as cache size and model name? I know I can set CPU features, topology and pinning and ...
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1k views

Debian Jessie Qemu KVM GPU Passthrough to Windows Virtual Machine guest Virt-Manager error Bus PCI not found

I'm having problems with Virt-Manager not wanting to boot a VM and giving error: Error starting domain: internal error: process exited while connecting to monitor: char device redirected to ...
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1answer
80 views

Qemu+libvirt+kvm significant performance lag in VM's

I am troubleshooting poor performance on our new VM host machine which is a Dell PowerEdge R415 with hardware RAID. We've got about 20 VM's running like this: qemu-system-x86_64 \ -enable-kvm \ ...
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1answer
59 views

Unable to import Ubuntu virtual machine on Centos 7 kvm host

[root@kvm ~]# virsh create /root/ns1.jesse64.xml error: Failed to create domain from /root/ns1.jesse64.xml error: internal error: process exited while connecting to monitor: qemu-kvm: -machine ...
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3answers
2k views

How can I change Qemu KVM machine architecture from 440fx to q35 with virsh edit or virt-manager

Still trying to get GPU passthrough working and decided to change machine type from older 440fx to q35 ie pc-q35 but if I do virsh edit on the config it refuse to save saying "PCI Bridges not ...
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1answer
45 views

Convert virtual disk image to physical disk?

I'm trying to use QEmu for Windows to convert a virtual disk image to a physical SSD. But I'm not sure about the syntax for the output_filename parameter. Here's what I tried: qemu-img convert -p ...
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3answers
2k views

How to efficiently share host's folder with KVM guests?

I am configuring the service which stores plenty of files uploaded by nginx in /srv/storage dir on host system. These files are processed by worker KVM guests which may create new files or assign ...
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94 views

qemu-img VHD to raw image convert results in bad geometry:

Is anyone else able to reproduce this? Using StarWind V2V Image Converter on Windows, I'm able to get a valid disk.img file, so the source image.vhd is clean (pulled down from rackspace). Is this a ...
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12 views

libvirt hook qemu suse12

we have this qemu hook. In suse 11 was working well but in suse 12 it is not working. The hook is setting the ports in openvswitch native-untagged. Do you know if there is some libvirt missing ...
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54 views

OpenNebula glusterfs cannot create on volume

I try to create a VM on my gluster volume, it fails with the following message: Wed May 20 20:37:30 2015 [Z0][DiM][I]: New VM state is ACTIVE. Wed May 20 20:37:30 2015 [Z0][LCM][I]: New VM state is ...
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1answer
53 views

How much of a performance does using QEMU virtualization incur on Windows?

How much of a performance does using QEMU virtualization incur on a Windows host, when both the host and vm are running the same CPU? Older articles indicate that using kqemu avoided the slow down in ...
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3answers
74 views

Version control for virtual disk images

Is there any existing system for efficiently tracking the version history of a virtual disk image? Essentially, I have a disk image which is used as a "template" root filesystem for testing programs. ...
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1answer
123 views

Enabling Qemu/KVM Filesystem Passthrough Centos 7

I have a system running Centos 7 with the stock qemu/KVM code. I have several virtual servers running on this system and would like to enable the filesystem passthrough option. So far, I have not ...
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45 views

Why are Windows XP and 7 qemu/kvm guests not recognizing updates to a local Samba share?

I develop cross-platform software and test the Windows ports with wine, Windows XP, and Windows 7, the latter two tested using qemu with KVM. I also have several versions of OS X and Debian Wheezy as ...
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107 views

qemu-img snapshot on live VM

I have created multiple KVM VMs using QCOW2 images. Each VM has its own qcow2 file and is not based on any backing file. My question is specifically related to snapshots of QCow2 images on these ...
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1answer
2k views

Any way to convert qcow2 to ovf?

In our application we are downloading a qcow2 image and after that we are supposed to import that as OVF. So any way to convert qcow2 --> OVF or qcow2 --> vmdk(using qemu-img convert) --> ...
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1answer
182 views

How to configure and use qemu-guest-agent in Ubuntu 12.04? My main aim is to get the IP address of guest VM from Host machine

In the documentation it is not very clear that how to install and use qemu-guest-agent in Ubuntu 12.04. So can anyone help me out ? http://wiki.libvirt.org/page/Qemu_guest_agent It is a daemon ...
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2answers
1k views

How to speed up QEMU on Windows host?

We want to run our Ubuntu 64bit web server virtualized/emulated on a Windows 64bit host. Intended use is to distribute the VM to customers who might not have "elevated" or "admin" rights on the ...
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29 views

I added space to a kvm img file but the physical extents do not show up in lvm

I ran qemu-img resize kick.img +12G and thought I'd see some free physical extents when running pvdisplay but nope. When I run virt-filesystems --long --parts --blkdevs -h -a kick.img I see the space ...
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1answer
84 views

CentOS Qemu+KVM lot of virtual machine processes

I am on host-machine with Centos 6.5, qemu+KVM and 2 virtual hosts in it (behind NAT). Both virtual hosts were configured with Virtual Machine Manager (one of them is with Windows 2003 and other with ...
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1answer
5k views

Read/write access for passthrough (9p) filesystems with libvirt/qemu?

I have recently started experimenting with the support for passthrough filesystems in recent versions of KVM/QEMU/libvirt. Making the filesystems available for read access has "just worked", but I'm ...
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1answer
34 views

libvirt management is slow under ubuntu

I've just done a fresh install of KVM/Qemu under Ubuntu 14.04.2 on an older (C2D gen) server with dual quad core xeons and 24 gb of ram. I'm finding that I'm waiting for operations in virsh for around ...
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82 views

KVM GPU passthrough working only with cirruslogic vga added, VM goes in paused state if remove cirruslogic and boot with passed-through gpu only

It seems I had this working once but maybe that was when my kernel wasn't trying to load the fglrx kernel module. (I think before it was loading 'radeon' module) Not sure if this was the issue/change ...
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3answers
357 views

attaching usb dongle to KVM VM

I'm struggling to connect a usb device, that gets detected correctly by the host, to a kvm vm. I have a freshly installed Ubuntu Server 14.10 as KVM/QEMU host. I set up an Ubuntu vm using this ...
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2answers
374 views

qemu-kvm fail to boot Centos 5.3 after Kernel update at the host (feodra)

After updating Fedora 18 to kernel 3.9.x (current 3.9.4), I can no longer boot my Centos 5 guest OS. When I try to boot, the process halt at start and the CPU core work at 100%. If I boot Fedroa ...
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1answer
102 views

How to start a new instance of QEMU based on the same image and snapshot?

I have a QEMU image (qcow2) with a snapshot stored in it. Right now I'm using libvirt to start it. However, I want to be able to run more than one instance of the same image snapshot. I guess I can ...
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1answer
1k views

Which is better image format, raw or qcow2, to use as a baseimage for other VMs?

I am using a baseimage and based on that creating many VMs. And now I want to know which is better, qcow2 or raw to use for a baseimage. Moreover, can you please tell me if there is any advantage of ...
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1answer
65 views

Revert libvirt external snapshot

Having some issues understanding how to revert snapshots on ubuntu 14.04 using KVM... Until now i have been using internal snapshots, however due to space issues (space not being re-allocated after ...
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0answers
19 views

What is the maximum number of VM which can be used for a single baseimage? [duplicate]

In my current project I am using KVM hypervisor and qcow2 as a base image. On that base image I am creating many VMs, say 100s of VMs. So, my question is that will that baseimage be a bottleneck for ...
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2answers
3k views

How to start qemu directly in the console (*not* in curses or SDL)

I seem to recall being able to start qemu with only the terminal emulator output, with the graphic window disabled. And here I don't mean with the ncurses interface, that one is nice, but I want the ...
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2answers
434 views

Extremely slow qemu storage performance with qcow2 images

I'm running some images using libvrit on a small Openstack cluster. Storage performance on these machines is extremely poor: my monitoring tool shows 100% utilisation (usually on writes but sometimes ...
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2answers
106 views

How to measure boot time of a VM from host machine?

On both Guest machine and host machine, I am using Ubuntu 12.04. As a hypervisor I am using KVM. I want to perform some experiments related to boot-storm and I have created all other scripts to ...
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220 views

Backup KVM running machine safely

I read some solutions to make backups of running VMs, but all take offline snapshots that seems difficult that will work if the VM has high I/O load. I have tested but i have doubts about the process ...
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1answer
156 views

Qemu Proxmox VM - Network access to guests for BackupPC backups

Environment I rent a dedicated server from OVH and installed Proxmox 3.3 (which is based on Debian 6 Wheezy) in order to create and manage multiple Virtual Machines on it. Each VM is configured to ...
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1answer
244 views

Extremely slow disk IO in qemu-kvm VM

I have a VM running Debian Woody (kernel 2.4.18). Qemu-2.1.2, 2 CPU cores, 512M RAM, qcow2 image connected as IDE, ext3. The issue is that disk IO is slow. Here is a result of dd "benchmark" right ...
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2answers
3k views

Is there any way to shrink qcow2 image without converting it raw?

Is there any way to shrink qcow2 image without converting it raw? I cannot convert it to raw because I don't have disk space enough for raw image.
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1answer
450 views

How to install kvm in Debian (Lenny) over powerpc

I want to install kvm on debian(lenny). I have learnt that packages kvm and qemu-kvm are not available for powerpc architecture. I have found two packages(kvm-source & qemu) and installed it. Now, ...
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125 views

Force libvirt to pass always the same device number to the guest on USB device reconnection

I have a HP plotter connected with a USB cable to a debian server through a USB hub. On the server there is a virtualized Windows XP. Everytime I reboot the plotter a different device number is ...
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128 views

QEMU/KVM port forwarding issues

I'm trying to access websites hosted on a QEMU/KVM debian virtual machine from a Ubuntu host machine and other PCs/devices on the host machine's network. Later, I'd like to access this from the ...
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85 views

gluster libgfapi HA

I was exploring KVM_qemu with gluster distributed storage. My goal was to build a test cluster with complete HA . i.e HA for VMs as well as gluster storage . I'm planning to setup a 3 node gluster ...
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1answer
131 views

Changing qemu/libvirt default gateway IPv4 IP to something other than x.x.x.1/24

General info: I have a KVM-libvirt/qemu running on ArchLinux; 3.18.2-2-ARCH ls | egrep -i 'libvirt|qemu' libvirt-1.2.11-1-x86_64.pkg.tar.xz libvirt-glib-0.2.0-1-x86_64.pkg.tar.xz ...
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40 views

QEMU stop/continue memory releasing

When using qemu-monitor console, i do PAUSE / CONTINUE of different VMs with stop/cont commands, which works ok, and my main CPU usage stays low. Is it possible to keep memory usage low this or ...
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23 views

mounting logical volume attached to vm while vm is running

i am experimenting lvm2 and qemu-kvm. and I want to share and ask some questions. at the end of there is appendix what i am doing. a logical volume on host is attached on guest host (vm) as vda. this ...
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296 views

virt-install fully automated install

I'm looking into ways of installing/deploying a VM completely automated (no user interaction). So far I have tried QEMU and virt-install along with QEMU. The issue with qemu is that injecting ...
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2answers
860 views

Disable TCP checksum offloading on KVM virtual network

I have a virtual network for connecting KVM guests with the host. I need to disable TCP checksum offloading on this network. The ethtool works fine but I want to disable it permanently and I could ...