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- | Alright, I am completely re-writing this as the old notes were just out of date and incomplete. | + | To make a VM from the command line, do the following. Note that this recipe assumes you have already created your virtual switch, br0. It also presumes you have already created your virtual disk, and if you have not, simply run '' |
- | sudo nano /etc/network/interfaces | + | sudo virt-install --name=new.img \ |
+ | --os-type=Linux \ | ||
+ | --os-variant=debian10 \ | ||
+ | --vcpu=1 \ | ||
+ | --ram=2048 \ | ||
+ | --disk path=/mnt/vms/students/ | ||
+ | --graphics spice \ | ||
+ | --location=/ | ||
+ | --network bridge:br0 | ||
- | That file should look like this (adjust | + | To clone an existing image, do the following: |
+ | |||
+ | virt-clone \ | ||
+ | --original=clean \ | ||
+ | --name=sequoia \ | ||
+ | --file=/ | ||
+ | |||
+ | If you have a legacy image that needs to be larger, then install a few tools and the proceed to expand the virtual hard disk as follows: | ||
+ | |||
+ | apt install qemu-img kpartx | ||
+ | qemu-img resize debian10.img +50G | ||
+ | |||
+ | After expanding the virtual hard disk, open gparted in X passthrough / command line and expand the existing partition into as much of the the new space as you prefer. And to rename a VM (domain), do the following: | ||
+ | |||
+ | virsh shutdown < | ||
+ | virsh domrename < | ||
| | ||
- | #eth0 (alt name ent8s0g) physical host base-connection | + | To delete a domain, virt-manager uses the undefine command. To remove the accompanying storage with it, parse the command as follows: |
- | auto ent8s0g0 | + | |
- | iface ent8s0f0 inet static | + | |
- | address 8.25.76.160 | + | |
- | netmask 255.255.255.0 | + | |
- | gateway 8.25.76.1 | + | |
- | nameservers 8.8.8.8 | + | |
- | #eth1 (alt name enp8s0g1) interface for bridge | + | |
- | auto enp8s0g1 | + | |
- | iface enp8s0g1 inet manual | + | |
- | auto br0 | + | |
- | iface br0 inet static | + | |
- | address 8.25.76.159 | + | |
- | netmask 255.255.255.0 | + | |
- | gateway 8.25.76.1 | + | |
- | bridge_ports enp8s0g1 | + | |
- | nameservers 8.8.8.8 | + | |
- | Once that's done, run '' | + | virsh undefine guest1 --remove-all-storage |
+ | |||
+ | If you need to force stop a machine, virt-manager uses the destroy command, as follows: | ||
+ | |||
+ | virsh destroy guest1 | ||
+ | |||
+ | I prefer | ||
- | | + | |
- | echo nameserver 8.8.8.8 > /etc/resolv.conf | + | qemu-img convert -p -f qcow2 -O raw guest1.qcow2 guest1.raw |
| | ||
- | Next up, it is time to configure | + | If you do end up using this, then you will need to edit the virtual |
- | | + | |
+ | <driver name=' | ||
+ | <source file='/mnt/vms/ | ||
+ | |||
+ | Another essential tool is the ability to create snapshots and, when necessary, revert to them. Here are the commands to create snapshot1 and then later revert to that specific snapshot. | ||
- | This file should look like this (adjust to your use-case - and again, this is **inside | + | virsh snapshot-create-as guest1 snapshot1 --description "first snapshot 11-13-22" |
+ | virsh snapshot-revert guest1 snapshot1 | ||
+ | |||
+ | If you don't care about naming | ||
- | | + | |
- | | + | |
- | | + | To create an external snapshot, append the following arguments: |
- | netmask 255.255.255.0 | + | |
- | gateway 8.25.76.1 | + | |
- | nameservers 8.8.8.8 | + | |
- | The VM interface is listed inside the guest/ | + | virsh snapshot-create-as guest1 snapshot1 |
+ | |||
+ | If you want to revert | ||
- | | + | |
- | ip a | + | |
- | sudo apt install resolvconf | + | |
- | sudo nano / | + | |
| | ||
- | Enter the name server as follows: | + | If you need to delete a particular snapshot, or delete all children of a snapshot, execute: |
| | ||
- | | + | |
+ | virsh snapshot-delete guest1 --current --children-only | ||
- | At this point, I would probably reboot | + | |
+ | To list all snapshots for a particular guestOS, execute | ||
+ | |||
+ | virsh snapshot-list guest1 | ||
+ | |||
+ | To get information about the snapshot, these commands help: | ||
+ | |||
+ | virsh snapshot-info guest1 snapshot | ||
+ | virsh snapshot-dumpxml guest1 snapshot1 | ||
+ | |||
+ | If you need to make a live backup, do the following (Note: make sure that '' | ||
+ | |||
+ | |||
+ | virsh domfsfreeze guest1.qcow2 | ||
+ | qemu-img create -f qcow2 -b guest1.qcow2 snapshot.qcow2 | ||
+ | virsh domfsthaw guest1.qcow2 | ||
+ | |||
+ | |||
+ | At times you may need to resize or gather information about a particular virtual disk. If they are in the qcow2 format, gather information as follows: | ||
+ | |||
+ | qemu-img info disk.qcow2 | ||
+ | |||
+ | To regain space that is being used needlessly, you can sparsify the qcow2 disk. Note that you must install virt-sparsify separately with '' | ||
+ | |||
+ | virt-sparsify --in-place disk.qcow2 | ||
+ | |||
+ | Most importantly, | ||
+ | |||
+ | cp -ar --sparse=always disk.qcow2 disk.bk.qcow2 | ||
+ | qemu-img resize disk.qcow2 1000G | ||
+ | qemu-img resize disk.qcow2 +10G | ||
+ | |||
+ | Okay, so another big issue with qcow2 images is them growing over time from writes/ | ||
+ | |||
+ | sudo systemctl enable fstrim.timer | ||
+ | sudo systemctl start fstrim.timer | ||
+ | |||
+ | You can also manually run fstrim | ||
+ | |||
+ | fstrim -v / | ||
+ | qemu-img convert -O qcow2 guest.qcow2 guest-trimmed.qcow2 | ||
+ | qemu-img convert -O qcow2 -c guest.qcow2 guest-trimmed.qcow2 | ||
+ | |||
+ | To test trimming functionality, | ||
+ | |||
+ | dd if=/ | ||
+ | |||
+ | To create a backup volume inside a guest you create the volume, attach it, and then shell into the guest and format, mount, and create an fstab entry. First, on the hostOS: | ||
+ | |||
+ | cd / | ||
+ | qemu-img create -f qcow2 vm1-backup.qcow2 32G | ||
+ | virsh attach-disk guestOS.qcow2 \ | ||
+ | --source / | ||
+ | --target vdb \ | ||
+ | --persistent | ||
+ | |||
+ | Then, on the guestOS: | ||
+ | |||
+ | mkdir / | ||
+ | mkfs.ext4 /dev/vdb | ||
+ | mount -t auto /dev/vdb / | ||
+ | nano / | ||
+ | /dev/vdb /mnt/backup ext4 defaults, 0 0 | ||
+ | |||
+ | The rest from here on out is my attempt at resizing an .img virtual disk using tools exclusively from virsh / virt-manager. These are highly risky moves and totally not needed for day to day operations. It was more of a mission I was on and based on a tutorial I used nearly 15 years ago when expanding a Windows VM I used for teaching software | ||
+ | |||
+ | sudo apt install libguestfs-tools | ||
+ | |||
+ | After that, confirm the location of your virtual machine. | ||
+ | |||
+ | virsh dumpxml putnameofimagehere | xpath -e / | ||
+ | |||
+ | Navigate to the directory it spit out, and back up the image and rename it before you proceed: | ||
+ | |||
+ | cd / | ||
+ | sudo cp / | ||
+ | |||
+ | Once you know the name of the .img file and the location of it, prepare the virtual file systems for expansion: | ||
+ | |||
+ | virt-filesystems --long --parts --blkdevs -h -a / | ||
+ | |||
+ | Build a new, larger, container for the final disk, and set it aside for the merge/ | ||
+ | |||
+ | truncate -s 128G / | ||
+ | |||
+ | Now it is time to resize the existing image, using the container | ||
+ | |||
+ | virt-resize --expand /dev/sda2 / | ||
+ | |||
+ | Okay, now we need to rename the new image we created to the name that virt-manager is looking for, i.e., the name of the original image. | ||
+ | |||
+ | cp / | ||
+ | mv / | ||
- | --- // | + | Made yet another attempt to do by command line in 2022. Install packages required for resizing virtual hard disks and for listing partitions inside virtual hard disks. |
+ | |||
+ | apt install qemu-img kpartx | ||
+ | |||
+ | Add 50G of size to the emulated physical hard disk. This is not to be confused with adding space to, or extending, the partition inside it. | ||
+ | |||
+ | qemu-img resize debian10.img +50G | ||
+ | |||
+ | Mount the image file in the present directory, and show all of its mappings. | ||
+ | |||
+ | kpartx -v -a debian10.img | ||
+ | |||
+ | Now, it is time to extend the partition. Your loops might have different #s after, use tab to find the right one (prolly largest #). | ||
+ | |||
+ | parted /dev/loopXX print | ||
+ | |||
+ | You will get output like this: | ||
+ | |||
+ | Model: Unknown (unknown) | ||
+ | Disk / | ||
+ | Sector size (logical/ | ||
+ | Partition Table: loop | ||
+ | Disk Flags: | ||
+ | Number | ||
+ | | ||
+ | |||
+ | Remove the appropriate mapping. In my case, I am extending the boot volume of a virtual machine, so it was entry 1. | ||
+ | |||
+ | parted /dev/loopXX rm 1 | ||
+ | |||
+ | Extend the partition from the start of the mapping you removed to the upper size limit listed in Disk. | ||
+ | |||
+ | parted /dev/loopXX mkpart primary ext4 0.00B 142GB | ||
+ | |||
+ | Verify the new mapping. | ||
+ | |||
+ | parted /dev/loopXX print | ||
+ | |||
+ | Run fsck before resizing the file system. You here appending " | ||
+ | |||
+ | e2fsck -f / | ||
+ | |||
+ | Extend the file system inside the partition to the entirety of the partition table. | ||
+ | |||
+ | resize2fs / | ||
+ | |||
+ | Unmount the image | ||
+ | |||
+ | kpartx -d debian10.img | ||
+ | |||
+ | --- // |