305-300 - LPIC-3: Virtualization and Containerization - Exam 305, version 3.0

 The command virsh list is used to list all running domains (VMs) on the current host. The command virsh list --all can be used to list both active and inactive domains. The other options are not valid virsh commands. The command virsh list is a basic command that lists all running domains (VMs). You can also list all configured VMs by adding the --all option. This is useful if you want to see all VMs configured in the target hypervisor that you can use on subsequent commands1. References:

• 1: 8 Linux virsh subcommands for managing VMs on the command line | Enable Sysadmin.

 The correct way to start a new container that shares the /data volume with the datastore container is to use the --volumes-from flag. This flag mounts all the defined volumes from the referenced containers. In this case, the datastore container has a volume named /data, which is mounted in the service container at the same path. The other options are incorrect because they either use invalid flags, such as --share-with or --volume-backend, or they create new volumes instead of sharing the existing one, such as -v datastore:/data or -v /data. References:

• Docker Docs - Volumes
• Stack Overflow - How to map volume paths using Docker’s --volumes-from?
• Docker Docs - docker run

The virt-diff command-line tool can be used to list the differences between files in two virtual machines or disk images. The output shows the changes to a virtual machine’s disk images after it has been running. The command can also be used to show the difference between overlays1. To specify two guests, you have to use the -a or -d option for the first guest, and the -A or -D option for the second guest. For example: virt-diff -a old.img -A new.img1. Therefore, the correct command to list all differences between the disk images vm1-snap.img and vm1.img is: virt-diff -a vm1-snap.img -A vm1.img. The other commands are not related to finding differences between disk images. virt-delta is a tool to create delta disks from two disk images2. virt-cp-in is a tool to copy files and directories into a virtual machine disk image3. virt-cmp is a tool to compare two files or directories in a virtual machine disk image4. virt-history is a tool to show the history of a virtual machine disk image5. References:

• 21.13. virt-diff: Listing the Differences between Virtual Machine Files …
• 21.14. virt-delta: Creating Delta Disks from Two Disk Images …
• 21.6. virt-cp-in: Copying Files and Directories into a Virtual Machine Disk Image …
• 21.7. virt-cmp: Comparing Two Files or Directories in a Virtual Machine Disk Image …
• 21.8. virt-history: Showing the History of a Virtual Machine Disk Image …