KVM (for Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, ...

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KVM booting off-image kernel and existing partition

I am in the process of switching from Xen to qemu-kvm. My current Xen installation has a number of LVM volumes each with a partition (rather than a full disk image). In Xen, I start each VM with a ...
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2answers
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Mount LVM within a disk image

I have a disk image that I made with KVM. The partition layout inside the disk image is as follows. [root@centreon01 2tb-external]# fdisk -lu vdisk1.img Device Boot Start End ...
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419 views

KVM: Machines unbootable after host reboot

Im finding that my KVM guests are unusable after i reboot my host. Specifically, I always get this error: Booting from hard disk Boot failed: not a bootable disk What causes this error? ...
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Adding Virtio block devices at runtime in Libvirt KVM

I'm running Debian Wheezy Beta 4 with KVM based guest systems which run the same operating system. I'm using LibVirt to manage the virtualisation. What I would like to do is to attach an LVM based ...
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1answer
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Use one NIC to create multiple interfaces for Linux KVM

I am working on a thesis research project, and I am having some difficulty figuring out how to make one NIC spawn several "bridge" interfaces such that each KVM VM can be seen on the local network. I ...
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KVM online disk resize?

We're evaluting KVM for Linux virtualization on a few projects. All is going well so far. But one of our requirements is the ability to add disk space to a running guest without rebooting or taking it ...
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4answers
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Convert directory to QEMU/KVM virtual disk image

I have a directory filled with data at /var/backups/disk1 that I want to convert into a virtual disk image which I'll then be able to boot using QEMU or KVM (the directory contains the file system for ...
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1answer
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Does kern.hz still have any relevance in FreeBSD if “dynamic tick mode” is enabled?

I'm running a FreeBSD 9.0 setup as a virtual machine in a KVM setup. In previous versions of FreeBSD it was common to force the kern.hz setting to a lower value so that the virtual machine does not ...
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1answer
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KVM virtual machines cannot reach IPv6 web sites

I have a freshly installed Windows Server 2008 R2 SP1 virtual machine which is completely unable to reach any IPv6 web pages, despite apparently having proper IPv6 connectivity. In addition, other ...
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3answers
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KVM “live migration finished” detection

I'm using KVM (through libvirt actually) for a research project. We're live-migrating a virtual machine between different subnets, so after the migration the IP address and routing tables have to be ...
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2answers
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Solidworks: activation license mode is not supported in this virtual environment (Qemu-KVM)

The question is not around Solidworks actually, so please continue to read. The whole idea of virtualization is to be hardware independent. Before our eyes a whole new dependency level is being ...
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1answer
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Why are eth0 and vmbr0 (bridge) having the same MAC addresses?

I configured my Debian (with KVM on board) as following: /etc/network/interfaces: auto lo iface lo inet loopback auto eth0 iface eth0 inet manual auto vmbr0 iface vmbr0 inet static address ...
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3answers
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sysctl.conf not running on boot

At what point is sysctl.conf supposed to be read during boot, and why might it not be running? I have the following settings which are not being applied when I reboot: ...
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6answers
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Will the OS crash if the system partition can't be access for a short period?

An operating system is installed in a virtual machine environment, such as VMWare or KVM. A network shared disk volume (e.g., iSCSI disk) is used as the OS system partition. Heavy traffic is running ...
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2answers
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How to install virtIO drivers for Win 2008 on KVM?

This is a follow up to a pervious question. I have a Ubuntu host with a Win 2008 KVM. To improve performance the network and IO - @dyasny and the documentation recommends installing virtIO drivers. I ...
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1answer
691 views

Ghost “vlan 0” tags added to ethernet frames in CentOS guest under OpenStack

I'm trying to debug an issue involving a KVM virtual machine instance where the instance doesn't respond to network requests when the source is on another physical machine, which is on the same subnet ...
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1answer
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Poor guest I/O performance KVM Ubuntu 12.04

I have a guest VM running inside a 12.04 Ubuntu host. VM was created using the vmbuilder python script. On the host the phoronix-test-suite "aio-stress" gives a performance speed of >1600MB/s Random ...
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1answer
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Linux-KVM / iptables: prevent guest spoofing by matching ip+mac address on bridge?

I have my KVM guests on a standard br0 bridge setup: auto br0 iface br0 inet static address 192.168.1.117 netmask 255.255.255.0 network 192.168.1.1 broadcast 192.168.1.225 gateway ...
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2answers
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KVM with one host IP and a different subnet for machines

I've already setup a KVM host with proper IP configurations, but my host had me create DHCP and use that to assign the IP's to the machines. I want to see if there's an easier way to do it (or ...
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1answer
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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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1answer
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High I/O latency with software RAID, LUKS encrypted and LVM partitioned KVM setup

I found out a performance problems with a Mumble server, which I described in a previous question are caused by an I/O latency problem of unknown origin. As I have no idea what is causing this and how ...
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1answer
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New KVM guests cannot access outside LAN

I have a KVM host (at 192.168.0.10) that currently has one working KVM guest (at 192.168.0.12). On attempting to install a new KVM guest today, I reached a problem where the network on the new guest ...
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1answer
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Pass an USB hub from a KVM host to a guest with libvirt

I have the following USB devices on a Linux server: # lsusb -t /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/2p, 480M |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M ...
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Slow disk I/O in KVM with LVM and md raid5

I have been battling with a kvm setup under debian for two weeks now, specifically with guest I/O disk performance. The system: -Supermicro 1018d-73mtf (X10SL7-F motherboard) -16GB ECC/UB -Intel ...
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1answer
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How to copy KVM disk image to LVM

Problem I'm getting a No space left on device error when doing a dd command. I'm trying to move a KVM qcow2 file to an LVM partition and thought that the LVM partition needed to be the same size as ...
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3answers
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KVM guest is unable to access the internet

I have a Debian host that has several allocated IPs and KVM with a Debian guest using a bridged network. The guest is completely unable to reach the network, including the LAN or even the host. ...
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3answers
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proxmox KVM routed network with multiple public IPs

I have a dedicated hosting with hetzner. Additionally i have bought a 6IP subnet. My main IP is: 148.111.111.200 My main subnet is: 255.255.255.224 My additional IPs are 148.222.222.1 to ...
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1answer
709 views

Why is there a socket interface on the host and a character device interface on the guest for virtio-serial?

I am trying to establish a communication channel between the host and one of its guest virtual machine using kvm as a hypervisor. For this, I am using virtio-serial. To create the virtual machine, I ...
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1answer
2k views

virt-install ignoring vnc port/listen?

I'm trying to create kvm machine on remote host. The host is running debian testing. Did use this command: virt-install --name debian-test \ --os-type=linux \ --os-variant=debianwheezy \ ...
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1answer
5k views

Centos/OVH: public IP on KVM virtual machine

Since a few days, I'm trying to configure my KVM vm to have a public IP address, without any success. First, I'm on OVH, and you need to know they don't allow networking from different mac addresses. ...
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1answer
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How to make sysctl network bridge settings persist after a reboot?

I am setting up a notebook for software demo purpose. The machine has 8GB RAM, a Core i7 Intel CPU, a 128GB SSD, and runs Ubuntu 12.04 LTS 64bit. The notebook is used as a KVM host and runs a few KVM ...
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2answers
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Multiple IP addresses assigned to one KVM VM

System: OS: Debian 6.0 64-bit with KVM installed from packages KVM is managed with Cloudmin 6.4.kvm I have a /29 subnet from my host. The bridge is setup properly for each VM to have its own IP, ...
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1answer
794 views

VPN SSTP windows client can not ping or connect to VPN server but it can talk to every other PC on the local LAN that VPN server is on

So I have an SSTP (with native Windows client) working fine in a sense. My windows client's local IP is 192.168.10.11 , so its local network is: 192.168.10.x The Remote VPN server is behind a router ...
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3answers
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Windows Server 2012 on KVM on Ubuntu 14.04. Runs well for a while and then slows down

I have Windows Server 2012 Essentials running as a VM on KVM running on Ubuntu 14.04 LTS. It performs very nicely after a reboot but after a while it starts slowing down and getting sluggish. This ...
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1answer
2k views

KVM guest time shift on host reboot

I have installed Ubuntu server 12.04 as a KVM host, and created an Ubuntu guest that is also running Ubuntu server 12.04. The servers are in the AST time zone which is UTC + 3 hours. After setting the ...
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1answer
1k views

Can KVM CPU assignment count differ from physical hosts CPU count?

I have read this question. I knew already that I could for example, have a quad core machine with four guests each having two vCPUs. As they don't all be require 100% CPU usage all the time, the ...
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2answers
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Can not boot CentOS VM using VirtIO in KVM

I converted qcow2 image to raw and changed I/O bus to VirtIO for a VM. now I can't boot that VM. I Installed VirtIO driver with following command: mkinitrd --with virtio_pci --with virtio_blk -f ...
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1answer
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KVM guests lose connectivity after networking restart

we're setting up an ubuntu server 10.04 host with kvm. The host is setup with a bond and bridged interfaces to allow the guests access to the network without natting. Our current configuration is ...
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1answer
2k views

Connecting to a KVM guest OS in Ubuntu

I am lost on this. Basically I am trying to set up a Ubuntu Server 10.10 as a virtual machine by using KVM. Everything went smoothly and I can even sudo-apt get packages from the guest OS. Now, ...
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1answer
1k views

ZFS virtualized on an LVM volume

We've got some large SATA disks kicking around, and I've been toying with the idea of throwing them in a KVM host and installing a FreeNAS VM to manage them. I'd be adding these via LVM to the host, ...
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1answer
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How to tell if VM in KVM is using VT-x

I have a machine running under KVM which is not performing very well. I have been trying to google a way to determine if a VM is using VT-x. I can find plenty of links on how to determine if your ...
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1answer
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ubuntu kvm disk io slowdown after some tyme

Host system: Ubuntu Server x64 12.04 mdadm raid 1 (/dev/sda /dev/sdb) no lvm dd bs=1M count=256 if=/dev/zero of=filename conv=fdatasync avarage ~ 40 MB/s NCQ on disks is disabled WriteCache is ...
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1answer
491 views

Access pty login prompt in VM

I have created a VM with virt-install, using as install media a Ubuntu 14.04.01 LTS server ISO. During the installation phase I was connected to the VM via the graphical console. Now I have the VM ...
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How can I make Windows Server 2012 running on KVM boot with virtio rather than IDE?

I have Windows Server 2012 Essentials running on KVM in Ubuntu 14.04. I've had some problems detailed here Windows Server 2012 on KVM on Ubuntu 14.04. Runs well for a while and then slows down I ...
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0answers
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Apache bench failing with error “No route to host”

Got a new dedicated box. Installed CentOS 6.5 Installed KVM Installed a CentOS 6.5 guest rsync'd websites/database/settings etc over from existing VPS. Set up "dedi.mydomain.com" in DNS to test it ...
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1answer
594 views

KVM Win 7 Pro + RH virtio net driver

Host: Debian 7.2 x64. Guest Win 7 Pro 32-bit. Virtio disk drivers work flawlessly, but there's a problem with virtio net (netkvm something) drivers. Virtio drivers come from virtio-win-0.1-74.iso. ...
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2answers
969 views

Why VM cannot get the public IP I have from provider?

I have a KVM-Host (on Debian) with root@kvm-host:/# cat /etc/network/interfaces auto eth0 iface eth0 inet manual auto vmbr0 iface vmbr0 inet static address 176.x.y.133 netmask 255.255.255.224 ...
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1answer
413 views

What are the differences in the configuration of the network on Proxmox (KVM)?

I have a dedicated server, one main public IP from /27 and two single public IPs also from the same /27 (I think the provider manages single IPs using the VLAN tags). I want to have a KVM running on ...
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1answer
176 views

KVM guest has a wrong outgoing ip address

I have a KVM host with a bridge configured on eth0 that has a public ip: auto br0 iface br0 inet static address xx.xx.aa.111 netmask 255.255.255.0 network xx.xx.aa.0 broadcast xx.xx.aa.255 ...
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3answers
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How to makesure VM is in Para virtualization mode on XEN?

I am having a server running XEN,with ubuntu 12.04 as Domain 0. Intel VT is turned on by default and i dont want to run any Windows OS as VM. So 1. how can i makesure that all the created VM will ...