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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33
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7answers
19k views

Replace VMware vSphere infrastructure with open source alternatives?

We are planning a slow migration from VMware (and third party apps) to open source alternatives (free would be great). Basically, we want to start with some little cluster lab, then migrate the ...
31
votes
7answers
59k views

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
votes
2answers
40k 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 ...
21
votes
6answers
43k views

How do you increase a KVM guest's disk space?

I setup an Ubuntu guest on a CentOS KVM host with initially 6GB of disk space. How do I go about increasing the Ubuntu guest's disk space from the command line? EDIT #1: I'm using a disk image file ...
16
votes
4answers
22k views

Is there a way to run virt-manager on Windows?

We've been using KVM for almost a year strictly on CentOS 5.x as the KVM host, with Fedora and Ubuntu workstations accessing the KVM host and its guests using virt-manager, virt-viewer, and ssh. Is ...
14
votes
2answers
7k views

Difference between KVM and QEMU

I have been reading about them 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 Operating ...
14
votes
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 ...
14
votes
3answers
24k views

How to connect a cdrom device to a kvm/qemu domain (using command-line tools)?

I have set up a virtual machine running Windows XP on my Ubuntu laptop. Using the virt-manager GUI application, I can insert a CD in my drive and go to Details→IDE CDROM 1 and click on the Connect ...
14
votes
6answers
27k views

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 ...
13
votes
5answers
2k views

Considerations when chosing AMD processors over Intel

I work for a company with a lot of legacy LAMP web-applications, where we are trying to refresh our hardware from ~250 physical servers to ~40 new servers w/virtualization. We have received two ...
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 ...
13
votes
6answers
2k views

recommendations for efficient offsite remote backup solution of vm's

I am looking for recommendations for backing up my current 6 vm's(and soon to grow to up to 20). Currently I am running a two node proxmox cluster(which is a debian base using kvm for virtualization ...
12
votes
4answers
7k views

how to rename a VM using libvirt+KVM

How can I rename a VM on KVM+libvirt? I would like it to change the name in the 'inventory' as well as change the name of the storage etc.
12
votes
4answers
22k 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 ...
11
votes
7answers
6k views

Tough Choice: Xen or KVM

I'm building a fresh workstation and want to use Linux alongside Windows. This seems like a good opportunity to get acquainted with with either Xen or KVM. So I face a choice. In favour of using ...
11
votes
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. ...
11
votes
4answers
7k views

Backing up qcow2 kvm guests

I can't find any good info on backing up qcow2 kvm guests. I'm not really interested in the guests running state, only the file system. This question suggests using savevm but that creates a snapshot ...
11
votes
3answers
11k views

Incredibly slow KVM disk performance (qcow2 disk files + virtio)

I'm having some serious disk performance problems while setting up a KVM guest. Using a simple dd test, the partition on the host that the qcow2 images reside on (a mirrored RAID array) writes at ...
11
votes
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 ...
10
votes
3answers
15k 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 ...
10
votes
1answer
12k views

KVM and Libvirt - How do I hotplug a new virtio disk?

I am trying to hot-add a file-based disk to a running KVM virtual server. I've created a new disk from scratch using the command dd of=/home/cloud/vps_59/test.img bs=1 seek=5G count=0 and I was ...
10
votes
5answers
4k views

what cluster management software to use for linux?

I have found the following cluster management software tools: pacemaker (clusterlabs.org), - original a Heartbeat project, focus for high-availability, will be in the next debian version openqrm ...
9
votes
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
votes
8answers
11k views

How do you synchronise huge sparse files (VM disk images) between machines?

Is there a command, such as rsync, which can synchronise huge, sparse, files from one linux server to another? It is very important that the destination file remains sparse. It may be longer (but ...
8
votes
8answers
1k views

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 ...
8
votes
3answers
9k views

Hyper Threading and Virtual Machines?

I already looked at this thread: Hyper-V and Hyper-threading: On or off?, but the only answer is Windows specific.... I am building a VM server (using Proxmox VE if that makes a difference) and was ...
8
votes
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 ...
8
votes
2answers
244 views

Can i pause VM's while power-cycling iscsi storage array

Unfortunately I may have to power-cycle my storage array. In the context of using KVM with libvirt managing the Virtual Machines where i need to power-cycle the storage array, is it possible or even ...
8
votes
2answers
2k views

Jumbo frames between KVM guest and host?

I am trying to implement a 9000 byte MTU for storage communication between KVM guests and the host system. The host has a bridge (br1) with a 9000 byte MTU: host# ip link show br1 8: br1: ...
8
votes
3answers
5k 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 ...
7
votes
2answers
2k views

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 ...
7
votes
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 ...
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 ...
7
votes
2answers
923 views

Linux-KVM networking advice?

Being new to virtualization in general, and somewhat new to Linux (using Debian Squeeze and coming from BSD) I have a hard time understanding what would be the best network bridging option for my host ...
7
votes
2answers
5k views

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 ...
7
votes
4answers
7k views

Can KVM suspend or shutdown guests automatically on host shutdown?

We have a CentOS 5.5 KVM host, running guests with various versions of CentOS and possibly other OSes later. We'd like to be able to either (a) automatically send an ACPI shutdown to all guests or ...
7
votes
2answers
2k views

Xen vs KVM: Which will have likely better support (read:bugfixes) in the future?

I don't care about GUI or tools, but I do care about stability and performance. If I'm running a FreeBSD firewall and a Opensolaris file server as guests, will I get better stability or performance ...
6
votes
3answers
3k views

How do you autostart a KVM VM with virt-manager? [duplicate]

I have some VMs that I need to be started when the host system is started. How do I set them to autostart?
6
votes
6answers
6k views

Get list of DHCP clients with KVM+libvirt?

I have several VMs running on Ubuntu 9.10 via KVM+libvirt. I want to be able to find out the IP address that has been assigned to each host without physically opening a physical "console" to each ...
6
votes
4answers
2k views

libvirt: Change dhcp-setup without restarting

I'm using libvirt and kvm to virtualize my server. I configured libvirt to start a dhcp-server on the bridge-network-interface to give the vm's their ips. Every VM's gets always the same ip based on ...
6
votes
1answer
7k views

Mapping USB drive direct to libvirt KVM virtual machine?

I am searching for information on mapping an existing drive (USB drive) to a KVM virtual machine using libvirt. I have been going over http://libvirt.org/formatstorage.html#StoragePoolTarget. But I ...
6
votes
2answers
4k views

Access KVM virtual machines over VNC without port forwarding with SSH

Is it possible to access the VMs without having to forward the remote port and VNC to the localhost? I'd like to be able to VNC into the KVM server and see the VMs display.
6
votes
1answer
964 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 ...
6
votes
4answers
952 views

Alternatives to Xen for virtualization setup

I currently use Xen in production to run a number of Ubuntu VMs (Intrepid/Jaunty). I've got another server which I'd like to set up as a VM host to run more guest OSes, and am looking for the best ...
6
votes
1answer
233 views

virtual disk image - file or partition

I'm looking at the differences between using a file versus a partition to store a virtual disk image in VM use. The common knowledge is that partition-based images are faster than file-based images ...
6
votes
1answer
539 views

kvm, vlans, how to simulate a 'mirror' port

I'm working with kvm 0.14.1 on an ubuntu lucid x64 box. I've got 3 vlans configured, one that is a bridge to the host's eth1. The others are host only. I want to start playing with snort. Is there ...
6
votes
1answer
702 views

Simulating a missing superblock error on EXT4 linux system

I'm trying to write reference material for a friend who has power outages a couple of times a year which affect their linux server. This person is not well versed in linux systems administration, so I ...
6
votes
3answers
4k views

For kvm host images. GFS2 or OCFS2 with drbd8?

I want a shared filesystem on top of drbd8 on two nodes. The servers run ubuntu 9.10. I googled a lot, but couldn't find an clear trend what the web community prefers. It's seems that OCFS2 is ...
5
votes
6answers
3k views

What is the perfect setup for a small Linux virtual server?

I have my own email server, and it serves a couple of dozen users. I need to replace it right now, and I want the replacement to be a virtual server image running under a hypervisor. My plans for ...
5
votes
2answers
15k views

What is bridge_fd?

I'm creating bridge network on Ubuntu 9.04(server) I set up following configuration file /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet manual auto br0 iface br0 ...