unix:virtualization:virtlib:quickreference
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unix:virtualization:virtlib:quickreference [2020/10/17 02:35] – rodolico | unix:virtualization:virtlib:quickreference [2023/02/26 17:12] (current) – rodolico | ||
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====== virt-lib Quick Reference ====== | ====== virt-lib Quick Reference ====== | ||
+ | |||
+ | virtlib stores its configuration for each //domain// (virtual) in / | ||
+ | |||
+ | The xml files are, well, xml. The format is documented at https:// | ||
===== virt-top ===== | ===== virt-top ===== | ||
Line 11: | Line 15: | ||
Some common commands are: | Some common commands are: | ||
* **list --all** - list all domains virt-lib knows about and show their state (running, off, whatever) | * **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 | ||
+ | * **domblklist //name//** - show attached block devices | ||
+ | * **domiflist //name//** - list all domain interfaces | ||
* **start //name//** - starts the domain named **name** (name from list --all) | * **start //name//** - starts the domain named **name** (name from list --all) | ||
* **reboot //name//** | * **reboot //name//** | ||
Line 18: | Line 27: | ||
* **autostart domain** - set domain to be autostarted in the future | * **autostart domain** - set domain to be autostarted in the future | ||
* **autostart --disable domain** - unset autostart flag for domain | * **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/ | * Attach/ | ||
- | * attach-interface | + | * attach-interface |
- | * detach-interface | + | * This will attach a new bridge to domain //domain//, using //bridge// defined on hypervisor, called vnet3 on the virtual, with the mac address set to whatever you use. |
+ | * detach-interface | ||
+ | * Remove virtual image (config file only)< | ||
+ | * **change-media //name// //drive//** - Insert or Eject a CDROM | ||
+ | * change-media //name// //drive// --eject | ||
+ | * change-media //name// //drive// // | ||
+ | |||
+ | ==== Boot from CD ROM ==== | ||
+ | |||
+ | This is actually not intuitive. I'm going to describe how to do this from a pretty complex setup with no GUI; adjust as needed. In this case, we need to boot the virtual myvirt from a gparted cdrom image located in / | ||
+ | |||
+ | Both assume the virtual has been turned off <code bash> | ||
+ | |||
+ | Some people do not want to manually edit the XML used to configure the virtuals, others prefer it. Some things, like setting a boot menu with a realistic timeout appear to require it; I have not found a way to do it through the virsh command. | ||
+ | |||
+ | I use the --config flag a lot. If you use this flag, any changes you make are written to the config file and will persist across boots. | ||
+ | |||
+ | === without manually editing configuration === | ||
+ | - First, see if there is a cdrom installed. One simple way is to dump the xml and grep for cdrom< | ||
+ | - Once this is done and you have a cdrom, you should be able to tell which one it is with< | ||
+ | - Mount your image on the CDROM | ||
+ | - If you have one and you know which drive it is<code bash> | ||
+ | - If you do not have a CDROM, use<code bash> | ||
+ | |||
+ | === I'm not afraid to edit the config === | ||
+ | - Edit the config file with <code bash> | ||
+ | - Look for something like //<disk type=' | ||
+ | - If it exists, add <code xml>< | ||
+ | - Look for the section //< | ||
+ | - <code xml>< | ||
+ | - This will enable the boot menu, and have a wait of 5 seconds (5000 milliseconds) for you to choose. | ||
+ | - If you want, change the boot order by adding <code xml>< | ||
+ | |||
+ | === Starting the virtual === | ||
+ | - Start the virtual with <code bash> | ||
+ | - Immediately make the VNC connection (if you followed the manual edit, you have 5 seconds) | ||
+ | - When prompted, press ESC to choose the CDROM drive (assuming you didn't set it as the default) | ||
+ | === Cleanup === | ||
+ | Do the following if you want to remove the CDROM when you're done. Note: this is likely required if you set the CDROM as the primary boot device. | ||
+ | <code bash> | ||
+ | |||
==== Remove a network from the entire system ==== | ==== Remove a network from the entire system ==== | ||
Line 36: | Line 87: | ||
</ | </ | ||
- | domxml | + | ==== New Install of Windows with virtio ==== |
+ | |||
+ | // | ||
+ | ]] will do the trick with only one extra step. | ||
+ | |||
+ | **Note**: You may have to manually start the virtual several times during the installation. Windows reboots 2-3 times during an installation, | ||
+ | |||
+ | - Add the --print-xml flag to virt-install, | ||
+ | - Manually edit the resulting xml file, adding a second cdrom drive (copy/ | ||
+ | - Change the drive letter | ||
+ | - Change the target to point to virtio-win.iso | ||
+ | - run <code bash> | ||
+ | - After installation is complete, install the remainder of the virtio drivers for maximum efficiency | ||
+ | - To permanently define after installation | ||
+ | - Edit XML and remove the second CDROM (if desired) | ||
+ | - <code bash> | ||
+ | |||
+ | |||
+ | ==== 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 / | ||
+ | </ | ||
+ | |||
+ | Normally, you attach/ | ||
+ | |||
+ | ==== 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 / | ||
+ | - Mount it on a running system< | ||
+ | - Create a temporary disk and attach it. Use virtio for the format of it. | ||
+ | - <code bash> | ||
+ | - 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 " | ||
+ | - Shut down your Windows guest | ||
+ | - Detach, then attach the primary drive.< | ||
+ | # 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 / | ||
+ | </ | ||
+ | - 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 should see QEMU Guest Agent running as a service. With this running, you can use qemu-guest-agent to manage shutdown and reboot. This is much more reliable than using ACPI. | ||
+ | |||
+ | **Important** Shut down the virtual before doing the following. | ||
+ | |||
+ | Edit the guest | ||
+ | <code bash> | ||
+ | virsh edit DOMAIN | ||
+ | </ | ||
+ | |||
+ | Place the following block under the < | ||
+ | |||
+ | <code xml> | ||
+ | <channel type=" | ||
+ | <source mode=" | ||
+ | <target type=" | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | Start the virtual back up. Once that is done you can use the following commands much more reliably. | ||
+ | <code bash> | ||
+ | virsh shutdown DOMAIN | ||
+ | virsh reboot DOMAIN | ||
+ | </ | ||
+ | |||
+ | This also allows you to execute // | ||
+ | |||
+ | ==== Using save/ | ||
+ | |||
+ | An alternative is to use //virsh save// to shut down and //virsh restore// to recover. In this case, use | ||
+ | <code bash> | ||
+ | virsh save domainname / | ||
+ | </ | ||
+ | to save the image. It will suspend the virtual, then save processor/ | ||
+ | |||
+ | Once this is done, you can do whatever you needed to do, then use the following command to restore it. | ||
+ | <code bash> | ||
+ | virsh restore / | ||
+ | </ | ||
+ | |||
+ | ==== 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. | ||
+ | |||
+ | This script has been tested on our machines, but I'm sure there are some issues with it. Just do a | ||
+ | <code bash> | ||
+ | virsh list --all | ||
+ | </ | ||
+ | and select the domains you want to ensure are running all the time. Place them in the array that has DOMAIN1 and DOMAIN2 (ie, replace DOMAIN1 with your first choice, etc...). | ||
+ | |||
+ | When called, checkVirtuals will look for each of the domains and see if they are running (using //virsh list//). If they are not running, it will place a flag file in / | ||
+ | |||
+ | I call this every 5 minutes from cron, thus, the max downtime will be 10 minutes, with an average of 5. | ||
+ | |||
+ | **WARNING: | ||
+ | |||
+ | <code perl checkVirtuals> | ||
+ | #! / | ||
+ | |||
+ | use strict; | ||
+ | use warnings; | ||
+ | |||
+ | my @servers = ( | ||
+ | ' | ||
+ | ' | ||
+ | ); | ||
+ | |||
+ | my $virsh = '/ | ||
+ | |||
+ | my $output = `virsh list`; | ||
+ | |||
+ | foreach my $server ( @servers ) { | ||
+ | if ( $output =~ m/$server/ ) { | ||
+ | unlink "/ | ||
+ | } else { | ||
+ | if ( -e "/ | ||
+ | print " | ||
+ | | ||
+ | | ||
+ | } else { | ||
+ | | ||
+ | } | ||
+ | } | ||
+ | } | ||
+ | |||
+ | 1; | ||
+ | |||
+ | </ | ||
+ | |||
+ | ===== 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 ##:##:##:##:##:## | ||
+ | # redefine it. Use values from above command, or change as needed | ||
+ | virsh attach-interface domain --type bridge --model virtio --source br_private --mac ##:##:##:##:##:## | ||
+ | </ | ||
+ | |||
+ | 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. | ||
+ | |||
+ | ===== Naming Network Links ===== | ||
+ | |||
+ | to give a domain interface a static name when it is run, you can add the following to the interface definition. | ||
+ | <code xml>< | ||
+ | NOTE: the name must not begin with ' | ||
+ | https:// | ||
+ | <code xml> | ||
+ | < | ||
+ | <mac address=' | ||
+ | <source bridge=' | ||
+ | <target dev=' | ||
+ | <model type=' | ||
+ | <address type=' | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | You can now do things like <code bash> | ||
+ | |||
+ | ===== Adding USB Drive Image ===== | ||
+ | |||
+ | Building and using a USB Thumbdrive image is a little weird, but it can be done. See [[software: | ||
+ | |||
+ | ===== Links ===== | ||
+ | |||
+ | * https:// | ||
+ | * https:// | ||
+ | * https:// | ||
+ | * https:// | ||
+ | * https:// | ||
+ | * https:// |
unix/virtualization/virtlib/quickreference.1602920109.txt.gz · Last modified: 2020/10/17 02:35 by rodolico