Qemu где хранятся файлы xml

Обновлено: 06.07.2024

KVM - это технология полной виртуализации для Linux на x86 (включая 64-bit) оборудование, содержащее расширения виртуализации (Intel VT или AMD-V). Сам KVM состоит из загружаемого модуля ядра, kvm.ko, который обеспечивает базовую инфраструктуру виртуализации и специфичный для процессора модуль, kvm-intel.ko или kvm-amd.ko.

В Debian, Xen и VirtualBox являются альтернативами KVM.

Установим пакеты qemu-kvm с помощью команды apt-get или aptitude, например, будем использовать следующую команду:

Демон libvirt будет запускаться автоматически во время загрузки и загружать соответствующие kvm модули, kvm-amd или kvm-intel, которые поставляются вместе с Linux ядром пакета Debian. Если вы намерены создавать виртуальные машины из командной строки, то установите virtinst.

Для того, чтобы иметь возможность управлять виртуальными машинами (ВМ) от обычного пользователя, вы должны добавить этого пользователя в группы kvm и libvirt:

Теперь вы можете получить список всех своих доменов:

libvirt defaults to qemu:///session for non-root. So from <youruser> you'll need to do:

You can use LIBVIRT_DEFAULT_URI to change this.

Самый простой способ для создания и управления гостевыми ВМ это использовать графическое приложение Virtual Machine Manager virt-manager.

Также, вы можете создать гостевую ВМ в командной строке. Ниже приведен пример для создания гостевой ВМ Debian Squeeze с именем squeeze-amd64:

Since the guest has no network connection yet, you will need to use the GUI virt-viewer to complete the install.

You can avoid pulling the ISO by using the --location option. To obtain text console for the installation you can also provide --extra-args "console=ttyS0":

Для полностью автоматизированной установке смотрите preseed или debootstrap.

Between VM guests

By default, QEMU uses macvtap in VEPA mode to provide NAT internet access or bridged access with other guest. Unfortunately, this setup could not let the host to communicate with any guests.

Between VM host and guests

To let communications between VM host and VM guests, you may setup a macvlan bridge on top of a dummy interface similar as below. After the configuration, you can set using interface dummy0 (macvtap) in bridged mode as the network configuration in VM guests configuration.

Between VM host, guests and the world

In order to let communications between host, guests and outside world, you may set up a bridge and as described at QEMU page.

For example, you may modify network configuration file /etc/network/interfaces for setup ethernet interface eth0 to a bridge interface br0 similar as below. After the configuration, you can set using Bridge Interface br0 as the network connection in VM guests configuration.

You can then use the virsh(1) command to start and stop virtual machines. VMs can be generated using virtinst. For more details see the libvirt page. Virtual machines can also be controlled using the kvm command in a similar fashion to QEMU. Below are some frequently used commands:

Start a configured VM guest "VMGUEST":

Notify the VM guest "VMGUEST" to graceful shutdown:

Force the VM guest "VMGUEST" to shutdown in case it is hanged, i.e. graceful shutdown not work:

On the other hand, if you want to use a graphical UI to manage the VMs, you can use the Virtual Machine Manager virt-manager.

Guest behavior on host shutdown/startup is configured in /etc/default/libvirt-guests.

This file specifies whether guests should be shutdown or suspended, if they should be restarted on host startup, etc.

First parameter defines where to find running guests. For instance:

Below are some options which can improve performance of VM guests.

Edit the VM guest configuration, assume the VM guest name is "VMGUEST" having 4 virtual CPU core

Disk I/O

Disk I/O is usually the bottleneck of performance due to its characteristics. Unlike CPU and RAM, VM host may not allocate a dedicated storage hardware for a VM. Worse, disk is the slowest component between them. There is two types of disk bottleneck, throughput and access time. A modern harddisk can perform 100MB/s throughput which is sufficient for most of the systems. While a modern harddisk can only provides around 60 transactions per seconds (tps).

For VM Host, you can benchmark different disk I/O parameters to get the best tps for your disk. Below is an example of disk tuning and benchmarking using fio:

Native driver for Windows VM guests
- Create new VM guest with below configuration:
  - IDE storage for Windows OS container, assume with filename WINDOWS.qcow2
  - IDE CDROM, attach Windows OS ISO to CDROM
  - Remove IDE storage for Windows OS, DO NOT delete WINDOWS.qcow2
  - Remove VirtIO storage for dummy storage, you can delete DUMMY.qcow2
  - Remove IDE storage for CD ROM
  - Add a new VirtIO / VirtIO SCSI storage and attach WINDOWS.qcow2 to it
  - Select VirtIO / VirtIO SCSI storage for the storage containers
  - Restart the VM guest
  - VirtIO SCSI storage provides richer features than VirtIO storage when the VM guest is attached with multiple storage. The performance are the same if the VM guest was only attached with a single storage.
  - Select "None" for disk cache mode
  - Edit the VM guest configuration, assume the VM guest name is "VMGUEST"
  Network I/O