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--- unix:virtualization:virtlib:quickreference [2020/10/17 02:25] – created rodolico
+++ unix:virtualization:virtlib:quickreference [2021/04/21 23:18] – rodolico
@@ Line 7: / Line 7: @@
 ===== virsh =====
-The main controller for virt-lib. The basic format of the command is <code bash>virsh command parameters</code>. Some common commands are:
+The main controller for virt-lib. The basic format of the command is <code bash>virsh command parameters</code>. //man virsh// or simply //virsh --help// are your friends.
+Some common commands are:
   * **list --all** - list all domains virt-lib knows about and show their state (running, off, whatever)
+  * **vncdisplay //name//** - show vnc display number (not port) assigned
+  * **dommemstat //name//** - show allocated RAM
+  * **domstats //name// | grep vcpu.current** - displays number of virtual cpu's assigned
   * **start //name//** - starts the domain named **name** (name from list --all)
+  * **reboot //name//**
+  * **shutdown //name//**
+  * **dumpxml //name//** dumps the config to STDOUT
+  * **list --autostart** - list all domains which will autostart
+  * **autostart domain** - set domain to be autostarted in the future
+  * **autostart --disable domain** - unset autostart flag for domain
+  * **console domain** - attaches to the serial console of domain assuming the port has been set up.
   * Attach/Detach network interfaces (https://computingforgeeks.com/managing-kvm-network-interfaces-in-linux/)
     * attach-interface --domain pxe --type bridge --source br1 --model virtio --config --live
     * detach-interface --domain pxe --type bridge --mac 52:54:00:47:2f:eb --config
+  * Remove virtual image (config file only)<code bash> virsh undefine domainname</code>
 ==== Remove a network from the entire system ====
@@ Line 28: / Line 41: @@
 </code>
-domxml to native
+==== New Install of Windows with virtio ====
+//virt-install// does not allow you to use two ISO's as cdrom images by default. This can be a problem when you want to do a new install, but want to use virtio on Windows (which requires a second ISO. You may be able to do a change-media, but the following, taken from [[https://superuser.com/questions/147419/using-virt-install-to-mount-multiple-cdrom-drives-images
+]] will do the trick with only one extra step.
+  - Add the --print-xml flag to virt-install, and pipe the output to a file.
+  - Manually edit the resulting xml file, adding a second cdrom drive (copy/paste)
+    - Change the drive letter
+    - Change the target to point to virtio-win.iso
+  - run virsh create name_of_xml_file to begin the installation
+==== Upgrading a disk to virtio (Unix) ====
+I messed up and did not use virtio as the bus for one of my setups, which resulted in horrible disk I/O. I could have rebuilt the virtual (it was a simple install and I had not gone very far), but I decided to learn how to do it the "right way". The trick here is to detach the disk, then re-attach it with the proper parameters.
+**Warning** Linux (and FreeBSD) have the virtio drivers built in, but Microsoft products do not. Read the section on Microsoft products if you are trying to do this with Windows.
+In my case, I wanted to reconfigure the boot drive, so I needed the machine down. It was running under the scsi bus, and I wanted virtio. Note that his is using LVM2 as the back end.
+<code bash>
+# get a list of all the block devices
+virsh domblklist router
+# detach the first drive (sda) from the domain router
+virsh detach-disk router sda --config
+# reattach it using the virtio bus.
+virsh attach-disk router /dev/vg/lvname sda --config --targetbus=virtio
+</code>
+Normally, you attach/detach disks from a running system. The --config parameter allows you to do it on an inactive domain; it just erases the entry, then rebuilds it.
+==== Upgrading a disk to virtio (Windows) ====
+For Windows, you need to have the correct device drivers installed before you change the disk. This assumes the domain is running
+  - Get a copy of the Windows VirtIO-win in iso onto your machine, someplace virsh can access, and mount the ISO
+    - Download ISO<code bash>cd /media/virtstorage && wget https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso</code>
+    - Mount it on a running system<code bash>virsh attach-disk domainname /media/virtstorage/stable-virtio/virtio-win.iso hdc --type cdrom --mode readonly</code>
+  - Create a temporary disk and attach it. Use virtio for the format of it.
+    - <code bash>virsh attach-disk domainname /path/to/disk/image sdb --targetbus=virtio</code>
+  - Open your console to the windows domain
+    - Find the new diskdisk (sdb). It will have a yellow triangle, indicating it can not be read because there is no device driver. Right click and say "Update Driver", then go find the drivers from the CD.
+    - Shut down your Windows guest
+  - Detach, then attach the primary drive.<code bash>
+# get a list of all the block devices
+virsh domblklist router
+# detach the first drive (sda) from the domain router
+virsh detach-disk domainname sda --config
+# reattach it using the virtio bus.
+virsh attach-disk domainname /dev/vg/lvname sda --config --targetbus=virtio
+</code>
+  - Start the Windows guest back up. Since the drivers are already installed, it should come back up.
+I did this with a Windows 10 installation on my workstation. Prior to using virtio, it would take, literally, 5-7 minutes after boot before I could do anything, and it was very sluggish after that. Once I used virtio, it was almost bare hardware speeds.
+===== Shutdown and restart of Windows guests =====
+==== Problems shutting down with //virsh// ====
+After installing the win-virtio package, you can use qemu-guest-agent to manage shutdown and reboot. This is much more reliable than using ACPI.
+Edit the guest
+<code bash>
+virsh edit DOMAIN
+</code>
+Place the following block under the <devices> section. I usually put it after the <console> sections, but just so long as it is in the <devices> section of the config. Virsh will rearrainge it for you anyway.
+<code xml>
+<channel type="unix">
+  <source mode="bind"/>
+  <target type="virtio" name="org.qemu.guest_agent.0"/>
+</channel>
+</code>
+You will need to restart the virtual before the changes take effect. Once that is done, however, you can use the following commands much more reliably.
+<code bash>
+virsh shutdown DOMAIN
+virsh reboot DOMAIN
+</code>
+==== Windows servers will not restart ====
+I'm having a problem with Windows virtuals not rebooting. When you issue the restart command, they shut off and don't come back up. As a band aid, I have a script running on the hypervisor with a cron job, every 5 minutes.
+===== Replacing Network Interfaces =====
+Sometimes you need to undefine and redefine a network interface. This is actually fairly simple to do.
+<code bash>
+# get a list of all network interfaces in domain
+virsh domiflist domain
+# remove the one you want. Use values (type, mac) from above command
+virsh detach-interface domain --type bridge --mac ##:##:##:##:##:## --config
+# redefine it. Use values from above command, or change as needed
+virsh attach-interface domain --type bridge --source br_private --mac ##:##:##:##:##:## --model virtio --config
+</code>
+In this example, //domain// is the name of the domain to be worked on. I use domiflist to get information about the network interfaces as I need the type and mac. The --config makes it permanent, writing it to the config file.
+In my case, I had built a Windows domain without using virtio, and I wanted to change it. This was actually the simplest way I found to do it.
+==== Links ====
+  * https://www.caretech.io/2017/10/18/converting-windows-vm-hard-disk-interface-to-virtio-with-proxmox-ve-5/
+  * https://docs.fedoraproject.org/en-US/quick-docs/creating-windows-virtual-machines-using-virtio-drivers/
+  * https://linuxhint.com/install_virtio_drivers_kvm_qemu_windows_vm/
+  * https://serverfault.com/questions/672253/how-to-configure-and-use-qemu-guest-agent-in-ubuntu-12-04-my-main-aim-is-to-get#691616
+  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_administration_guide/sect-qemu_guest_agent-running_the_qemu_guest_agent_on_a_windows_guest