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-img: Could not open $FILE

I received a single-file VMDK from a vendor that has a virtual appliance for a particular product I'm interested in evaluating. We run a KVM solution (Proxmox) so I tried converting the file but on ...
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970 views

KVM/Qemu Guest Shutdown problems

on both host and guest running CentOS 6.3 with KVM/Qemu virtualization, I have the following scenarios: "virsh shutdown kvm1" did not shutdown at all. virsh lists guest as running. "service ...
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Accessing the partitions on an LVM volume

Suppose you have an LVM volume /dev/vg0/mylv. You have presented this as a virtual disk to a virtualised or emulated guest system. During installation the guest system sees it as /dev/sda and ...
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406 views

Is it possible to pass /dev/urandom through from the host to a qemu/kvm guest?

I'd like to pass the host's /dev/urandom device through to a qemu/kvm virtual machine. Note that /dev/urandom is not seekable, so it's not possible to pass it through as a block device using -hda, ...
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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
166 views

Is it possible to run Windows as a Xen VM without VT, using Qemu-dm?

Is it possible to run windows as a virtual machine under Xen using qemu-dm? If so, how can it be done? Since Xen without VT technology supports only para-virtualization, can qemu-dm, the emulator ...
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conversion of a VMDK image with qemu-img failed with “error while reading sector 131072: Invalid argument”

I tried to convert a VMDK image found in a OVA file to the QCOW2 format with the qemu-img command but it failed with the error message qemu-img: error while reading sector 131072: Invalid argument ...
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does KVM raw images support preallocation?

I was trying to create a raw image with this command: qemu-img create -f raw -o size=200G,preallocation=metadata file.img but seem that it raw images doesn't support preallocation. if so why there ...
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1answer
252 views

KVM low network speed

I have a networking problem with KVM. There is only one VM on the server and port speed is 100 megabits per second But maximum download rate is about 1 megabytes per second and expected to be 10mb. ...
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673 views

Share CPU between two KVM VPS on a dedicated server

how can I share CPU between two KVM VPS on a dedicated server? assume that we have 8-core CPU on a dedicated server to get maximum performance for two VPS, should I assign 8 cores to each one of ...
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2answers
630 views

How to create LAN segments in qemu

I could successfully connect two different virtual machine ports directly using LAN segment feature in VMware workstation. Is there a way to do the same on qemu ? As of now i have created two qemu ...
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1answer
745 views

CentOS libvirt reboot

I've noticed the following status message after system update (on SL 6.1 - yum update): # /etc/init.d/libvirtd status libvirtd dead but pid file exists one of the updated packages was "libvirt". ...
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1answer
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Libvirt / QEmu Machine Fails and Refuses Restart Because of Memory Allocation Errors

I'm having a problem with libvirt. On a system restart all virtual machines (VMs) are started without a problem and keep running. Then at some point in time a set of machines shuts down according to ...
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4answers
21k views

KVM: Which CPU features make VMs run better?

We are using Ubuntu 12.04 with the following parameters: Dell R910 Kernel 3.2.0-25-generic #40-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux kvm 1:84+dfsg-0ubuntu16+1.0+noroms+0ubuntu13 qemu-kvm ...
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2answers
350 views

QEMU Virtual CPUs

I've seen that people run VMs with KVM and QEMU Virtual CPUs but when I'm creating a VM using virt-manager it only show my real cpu cores not virtual CPUs. how can I activate QEMU Virtual CPU? Thanks ...
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2answers
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kvm and qemu host: Is there a limit for max CPUs (Ubuntu 10.04)?

Today we encountered a really strange behaviour on two identical kvm and qemu hosts (Dell R910). The host systems each have 4 x 10 Cores, which means that 40 physical cores are displayed as 80 within ...
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3answers
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Is there a way to determine which virtual interface belongs to a virtual machine in a kvm host?

I'm using qemu/kvm whith bridged networking. In the host machine there are several "vnetX" network interfaces without IP. I'm looking for a way to know which vnetX belong to a virtual machine. I ...
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330 views

qemu/virt-manager no permisson on shared folder

I have a strange problem. Iam trying to create a shared folder via the add-hardware->filesystem option. For Type and Modus i choose Passtrought and for Driver Path. The Source Path is /free and target ...
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1answer
496 views

How to connect a virtual NIC in one QEMU-KVM instance to a virtual NIC in another QEMU-KVM instance without a bridge

Is there a way to connect a Virtual NIC one QEMU-KVM instance to a Virtual NIC on another QEMU-KVM instance. I want to be able to do this efficiently and it may be possible that the 2 instances could ...
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1answer
478 views

qemu with tun virtual networking issues

I'm trying to setup a virtual networking environment using open-wrt qemu and vde2 The script to boot two qemu instances and conenct them together is the following ...
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2answers
1k views

understanding relationship between Qemu and KVM

What is the difference between KVM and Qemu? As I understand, latter is able to provide "user mode emulation" which means that one can run a single executable built for some other architecture like ...
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Monitor VM's resources (CPU, RAM etc)

I'm testing Openstack and i'd like to know how can i find out about resource utilization inside instances (Virtual Machines). Openstack uses kvm, qemu and libvirt in my testing environment. Is there ...
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1answer
431 views

Routing table with two NIC adapters in libvirt/KVM

I created a virtual NAT network (192.168.100.0/24 network) in my libvirt and new guest with two interfaces - one in this network, one as bridged (10.34.1.0/24 network) to the local LAN. The reason for ...
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2answers
172 views

How to delete the MBR (Master boot record) out of an image file?

I have a QEMU image myserver.img that is about 20GiB. The file serves as a "virtual" hard disk for the server. Now the first 512 bytes contain the MBR, and I am trying to overwrite those bytes with ...
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1answer
282 views

FVD format on qemu/KVM

How can I install this format in Centos KVM?. Is it included in latest qemu versions? Reference in qemu wiki: http://wiki.qemu.org/Features/FVD Thanks in advice
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189 views

Host Websites on Virtual IP VMs

I have Proxmox Virtulization server installed. But i have one real(Public) IP. Incoming request to Proxmox server must be bind Virtualized servers. Dnsmasq installed in Proxmox Virtualization Server. ...
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3answers
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QEMU-KVM Linux virtualization on the command line

I recently discovered that qemu-kvm has a very promising -curses option that, instead of starting an X window, will show a nice ncurses output from the guest suitable for managing a Linux guest from ...
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2answers
146 views

Managing a QEMU guest from the host's CLI

Can I manage a QEMU guest from the host's CLI? I'm coming from Xen and I liked the xm command. I'd like to shutdown the guest, attach PCI devices to it and so on. Is there a way? There's the QEMU ...
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1answer
888 views

TCP/IP performance tuning under KVM/Qemu

With more and more companies switching to public cloud services, I'm curious what you guys' thoughts are on TCP/IP tuning in the cloud. Is it worth bothering with? Given that you don't have access to ...
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1answer
564 views

QEMU virtual networking NAT

I'm trying to set up a virtual network as described here. These are my steps: ifup eth0 # uses DHCP brctl addbr br0 ifconfig br0 up 192.168.0.1 kvm ... -device e1000,netdev=tap0 -netdev ...
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1answer
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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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How to quit QEMU monitor?

I launched KVM VM with this command: kvm /kvm/hdd/v1/v1-1.raw -m 512 -daemonize -smp 2 -nographic -net nic,model=virtio,macaddr=aa:aa:aa:aa:aa:01 -net tap,ifname=tap0 -monitor ...
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1answer
603 views

Fault-tolerant KVM hosts

I'm going to create a simple virtual hosts infrastructure using QEMU+KVM. It is expected to be very simple, without clouds or any other cool things. Right now the only requirement is the ...
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2answers
329 views

Software for managing a cluster of KVM physical hosts?

I am looking for software recommendations for managing a cluster of KVM physical hosts. We are currently using virsh and doing just about everything by hand, and I would like to find a slightly more ...
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2answers
3k views

qemu-kvm/virsh: No network connectivity whilst using bridged networking

I'm having an issue with performing virtualisation via libvirt/qemu-kvm, in which my set up for bridged networking doesn't appear to be working correctly. I've followed every tutorial I can find and ...
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1answer
861 views

How to convert OpenVZ OS template to bootable image file?

My question is how to convert a pre-created OpenVZ OS template which are in tar.gz format (such as these) to an image file in order to be able boot it with other virtualization solutions such as QEMU ...
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virt-rescue for Ubuntu

I want to install virt-rescue on Ubuntu 11.10 or Ubuntu 10.04. It could not be found in the repositories. Where can I get it?
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1answer
235 views

freebsd iso install on KVM - timer freezes

Trying to boot freebsd iso on KVM/libvirt [debian host] Timer shows: 10 sometimes is 9 or even 7. and that's it, count down stops.. Found some information that it's a bug with newest qemu and my ...
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1answer
452 views

Installing and running a guest OS on KVM-qemu with only serial console access

I am trying to installing a bsd distro with virt-installer. With a Linux distro I used this: virt-install -n debian -r 1024 --vcpus=1 --accelerate -v --disk ...
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2answers
6k views

free up not used space on a qcow2-image-file on kvm/qemu

we are using kvm/qemu with qcow2-images for our virtual machines. qcow2 has this nice feature where the image file only allocates the actually needed space by the virtual-machine. but how do i shrink ...
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3answers
368 views

Store QEMU images in database

I have a task to store QEMU images in a database and thinking towards developing of the custom block device. Is this a good idea? Where is it better to start from?
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1answer
1k views

Qemu: can I set the serial number on a virtual SCSI device?

I'm using libvirt+KVM+Qemu on Ubuntu 11.04. I have some scsi devices like this: <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source ...
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1answer
405 views

Give a KVM Guest only access to OpenVPN

I'm in a kind of weird situation where I need to do the following: Connect an OpenVPN tunnel with static RFC1918 IPs (think of 10.3.3.1 for the server end and 10.3.3.2 for the client end) and have it ...
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2answers
7k views

Changing boot device for a QEMU-KVM virtual machine

I am trying to change the boot device for a VM. I go to the VM's XML file in /etc/libvirt/qemu and set <boot dev='cdrom' />. Still, it attempts to boot from the harddrive instead of the cdrom. ...
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1answer
1k views

How to add a serial COM port to Windows server 2008 using Linux + KVM + Qemu?

We are using Linux + KVM + Qemu with libvirt on our servers to manage virtual WIndows 2008 Servers. The Host is Ubuntu 11.04. The point is on one of our Windows server 2008 guest, we need to connect ...
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1answer
1k views

Set Mac Address in QEMU/KVM properties file

I'm trying to set the mac address for my virtual machine in the virtual machine properties file. The properties file '102.conf' currently looks like this: name: vm1.mydomain.com bootdisk: ide0 ...
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1answer
532 views

Maximizing throughput of virtual file systems

I've been using a QEMU system to build software. The problem I've been having is that the system seems to suffer from extremely slow disk access. This is not necessarily a problem as it's not really a ...
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1answer
990 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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1answer
800 views

qemu-kvm save and restore in different machines - Offline migration

I am using KVM in cents 5.6. I am trying to do offline migration between two machines. I have a common NFS server. I initially save the state of the running VM (on machine1) to a state file using : ...
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1answer
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CentOS 5.4 No package qemu available

I'm trying to install qemu on CentOS 5.4(final) with: yum install qemu The result is: Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * addons: mirror.steadfast.net * ...