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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Virtualization: Guest in guest?

Does it make any sense to run a virtual machine with a "master" guest, and in that master guest run many other guests? Has anyone tested this? Is it even possible? Are there better ways to accomplish ...
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1answer
2k views

Getting windows virtio mounted/installed for KVM

There might be an easy answer to this. I have exhausted my search on google for a solution. Here's my problem. I need to get Windows working on a KVM vps with virtualizor CP. As I get into windows ...
3
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1answer
842 views

How can I run Startup Repair on a KVM virtualized Windows Server?

I have Windows Server 2008 R2 running virtualized in a KVM virtual machine. Recently the virtual machine decided to stop booting, and it offered to Launch Startup Repair. However, upon entering ...
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2answers
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Set startup order for KVM virtual machines via libvirt?

I have some server applications failing because their virtual machine starts up before the database virtual machines. Anyway to configure libvirt to start them up in a certain order and possible ...
11
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3answers
13k views

Snapshot/rollback for libvirt+KVM?

I've recently begun using KVM for my development/test environment on a Linux host system with 8G memory. Prior, I was using VMware Fusion for my virtual environment, but my Macbook only has 2G memory. ...
5
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1answer
9k views

KVM guest io is much slower than host io: is that normal?

I have a Qemu-KVM host system setup on CentOS 6.3. Four 1TB SATA HDDs working in Software RAID10. Guest CentOS 6.3 is installed on separate LVM. People say that they see guest performance almost equal ...
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4answers
9k views

Virtualized CPU cores vs. threads

We've got a KVM host system on Ubuntu 9.10 with a newer Quad-core Xeon CPU with hyperthreading. As detailed on Intel's product page, the processor has 4 cores but 8 threads. /proc/cpuinfo and htop ...
2
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3answers
4k views

How to automatically start VM created by virt-manager?

I have created a virtual machine with virt-manager that runs on kvm/qemu. The machine works well when started through virt-manager. However, I would like to be able to start and stop the VM through ...
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2answers
360 views

How do I configure bridged networking for VMs

I'm setting up a KVM virtualization server in CentOS 6. How do I configure bridged networking? (I think I need network interface eth0 to be accessible to VMs) I have tried to follow this guide: How ...
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2answers
1k views

Migration from Xen to KVM

I have Xen domU virtual machines running Windows. Each of them are installed in their own LVM logical volumes. I want to migrate them to another server with KVM on lvm to. How can I do this faster ...
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1answer
138 views

Consolidating a server and a desktop on one machine [closed]

What is the best way to have a server and a desktop OS on one machine, with the desktop being displayed on a monitor directly connected? Visualization, with each having a separate guest, seems ideal ...
2
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1answer
278 views

Persistent Network Configuration using KVM and libvirt

Our environment will have a KVM host setup dynamically using kickstart (easy enough). The hard part is dealing with network configuration and keeping VLAN configuration (and possibly bridge/host ...
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7answers
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Xen vs KVM in performance

What is faster on same hardware - Xen or KVM? I'm trying to pick-up a virtualization technology to work, which gives the best performance. There are some benchmarks here that I found on the subject: ...
28
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2answers
41k views

Difference between Xen PV, Xen KVM and HVM?

I know that Xen is usually better than OpenVZ as the provider cannot oversell in Xen. However, what is the difference between Xen PV, Xen KVM and HVM (I was going through this provider's specs? Which ...
11
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3answers
16k views

Forwarding ports to guests in libvirt / KVM

How can I forward ports on a server running libvirt/KVM to specified ports on VM's, when using NAT? For example, the host has a public IP of 1.2.3.4. I want to forward port 80 to 10.0.0.1 and port 22 ...
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6answers
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KVM Guest installed from console. But how to get to the guest's console?

I'm trying to install a fully virtualized guest (Fedora 14 x86_64) on KVM (RHEL 6), using command-line only (both hypervisor and guest). It goes without errors, and without a tangible result . I'd ...
7
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2answers
5k views

KVM on Illumos (OpenIndiana vs. SmartOS)

I'm considering virtualizing a number of guests onto a single server running a recent port of KVM to Illumos. It sounds like my two primary options will be OpenIndiana and SmartOS. The distribution ...
11
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4answers
6k views

KVM/qemu - use LVM volumes directly without image file?

I'm not quite sure how to phrase this question (hence the poor title), so let me provide an example of what I'm trying to do. On my (old) Xen host, I'm able to present LVM filesystems directly to ...
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2answers
6k views

Backup of KVM guests when using qcow2 disk files

I got a Ubuntu (hardy) system used for virtualization using KVM. Each guest got it's own qcow2 file used as disk. Guests are running Ubuntu (hardy). What would a good backup strategy be for such a ...
12
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4answers
23k 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 ...
6
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1answer
987 views

KVM/Qemu, Ubuntu: Why do more guests CPUs enhance Disk-I/O rapidly?

We have an Heartbeat/DRBD/Pacemaker/KVM/Qemu/libvirt cluster consisting of two nodes. Each node runs Ubuntu 12.04 64 Bit with the following packages/versions: Kernel 3.2.0-32-generic #51-Ubuntu SMP ...
2
votes
3answers
5k views

libvirt and qemu/kvm -snapshot option

Using libvirt, I want to use QEMU's '-snapshot' option. That way, when the machine shuts down, all of the disk changes that were made get destroyed. Here is the manual for the -snapshot option: ...
14
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4answers
5k views

Improving IO with FlashCache

I have a server with 2 HDD's (2x 1 TB), running in RAID 1 (SW-RAID). I want to improve IO performance by using flashcache. There are running KVM virtual machines on it, using LVM. Regarding this, I ...
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4answers
4k views

Port Forwarding from Host to Guest with libvirt 0.8.3 Using KVM on Ubuntu

The host has a single external IP available, so I set my KVM guests up with NAT. How do I set up a port forwarding to forward some of the requests from the outside to the guests? I couldn't find ...
8
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3answers
6k views

LVM volume group shared between KVM/libvirt host and guests: is this a bad idea?

I have just built a shiny new KVM/libvirt-based virtual machine host, containing 4 SATA II hard drives, and running CentOS 5.5 x86_64. I have decided to create virtual machine disks as logical ...
4
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1answer
2k views

Why does host swap out VMs when there are 16GB of buffer cache and swappiness = 0? [duplicate]

I have a desktop running Ubuntu Quantal using OpenStack Folsom on an Intel i5 with 32 GB RAM and 2 GB swap. I'm running 7 VMs each sized like a EC2 m1.small, so 1.7 GB RAM each. I'm using KVM. As I ...
4
votes
3answers
2k views

Is KVM stable enough for production use in 2011?

We are planning to virtualize the existing infrastructure by an open source virtualization solution. KVM and Xen are on the final list. Big cloud players are still using Xen, and we found that KVM is ...
3
votes
2answers
3k views

KVM on RHEL 6.1 makes host sluggish

I have been running RHEL 5.7 on a host just fine with several VMs (KVM). No major issues. Time came to upgrade to RHEL 6.1 as a few bugs had been fixed in this release. When I start a VM or two under ...
3
votes
2answers
1k views

Network freezes with KVM/libvirt and ip_forward = 1

I'm using KVM and libvirt and experience small network freezes on the host and the guests every 2-3 minutes or so. The freezes last 1-2 seconds. The used OS is Ubuntu 10 LTS server edition. I'm ...
3
votes
2answers
3k views

Debian: Should I add vlan interface into bridge for KVM?

I am setting up a Debian Squeeze box as a KVM host. I want to add multiple interfaces to each KVM guest so I want them to be on different VLANs. After reading about this, I believe the best method is ...
3
votes
1answer
3k views

KVM network bridge with public static IP for both host and guests

I have a Ubuntu 10.04 server with 2 public static addresses. There is a KVM guest (also Ubuntu) installed and running. What i want is to give the guest an IP of the host, so that both machines have ...
2
votes
2answers
6k views

KVM and virtual to physical CPU mapping

I'm a relative late comer to the virtualistion party, so you'll have to forgive me if this seems like an obvious question. If I have a server with 12 cores available, does each KVM guest have access ...
2
votes
2answers
2k views

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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1answer
3k views

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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3answers
3k views

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
15k views

pfSense Site-toSite VPN with OpenVPN connects but won't route traffic

Using two pfSense routers, I've created a shared-key VPN between 2 sites. Both routers are pfSense 1.2.2. The pfSense box at the client site is the gateway router for that site, but at the server ...
13
votes
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 ...
7
votes
3answers
4k views

use LXC under heavier virtualization (Xen, KVM,Hyper-V,VMVare)

Is it possible to use LXC under heavier virtualization (Xen DomU,KVM,Hyper-V,VMVare) ? I would like to use it as security (isolation) tool, the ability to limit resource consumption is not priority ...
5
votes
1answer
2k views

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 ...
5
votes
1answer
940 views

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 ...
3
votes
3answers
957 views

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 ...
2
votes
1answer
898 views

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 ...
2
votes
3answers
2k views

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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votes
2answers
9k views

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
171 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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0answers
454 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
2k views

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
793 views

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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votes
2answers
2k views

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 ...
5
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1answer
2k views

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 ...