Pass the LPI LPIC Level 3 305-300 Questions and answers with CertsForce

LXC implements system containers, which are a type of operating-system-level virtualization. System containers allow running multiple isolated Linux systems on a single Linux control host, using a single Linux kernel. System containers share the same kernel with the host and each other, but have their own file system, libraries, andprocesses. System containers are different from application containers, which are designed to run a single application or service in an isolated environment. Application containers are usually smaller and more portable than system containers, but also more dependent on the host kernel and libraries. Hardware containers, CPU emulation, and paravirtualization are not related to LXC, as they are different kinds of virtualization methods that involve hardware abstraction, instruction translation, or modification of the guest operating system. References:

1: LXC - Wikipedia

2: Linux Virtualization : Linux Containers (lxc) - GeeksforGeeks

3: Features - Proxmox Virtual Environment

IaaS is a type of cloud computing service that offers essential compute, storage, and networking resources on demand, on a pay-as-you-go basis. IaaS is one of the four types of cloud services, along with software as a service (SaaS), platform as a service (PaaS), and serverless12. IaaS eliminates the need for enterprises to procure, configure, or manage infrastructure themselves, and they only pay for what they use23. Some examples of IaaS providers are Microsoft Azure, Google Cloud, and Amazon Web Services.

 Packer is a tool that automates the creation of identical machine images for multiple platforms from a single source configuration. Packer works by creating an instance based on a source image, which is a pre-existing image that serves as a starting point. Packer then connects to the instance through a network connection, such as SSH or WinRM, and runs various commands and scripts to install and configure software within the instance. Packer then shuts down the instance and creates a new system image from it, which can be used to launch new instances. Packer supports many platforms, such as AWS, Azure, VMware, Docker, and others. Packer does not install any software or run any daemon within the target image, nor does it periodically connect to the running instances to re-apply the template. Packer also does not modify the source image directly, but creates a new image from the modified instance. References:

Packer by HashiCorp

HashiCorp Packer - Build Automated Machine Images

Introduction | Packer | HashiCorp Developer

Resource management for full virtualization is the process of allocating and controlling the physical resources of the host system to the virtual machines running on it. The hypervisor is the software layer that performs this task, by providing each virtual machine with a virtual hardware of a defined capacity that limits the resources of the virtual machine. For example, the hypervisor can specify how many virtual CPUs, how much memory, and how much disk space each virtual machine can use. The hypervisor can also enforce resource isolation and prioritization among the virtual machines, to ensure that they do not interfere with each other or consume more resources than they are allowed to. The hypervisor cannot provide fine-grained limits to internal elements of the guest operating system, such as the number of processes, because the hypervisor does not have access to the internal state of the guest operating system. The guest operating system is responsible for managing its own resources within the virtual hardware provided by the hypervisor. For example, the guest operating system can create an arbitrary amount of network sockets, as long as it does not exceed the network bandwidth allocated by the hypervisor. Full virtualization can pose limits to virtual machines, and does not always assign the host system’s resources in a first-come-first-serve manner. The hypervisor can use various resource management techniques, such as reservation, limit, share, weight, and quota, to allocate and control the resources of the virtual machines. The hypervisor can also use resource scheduling algorithms, such as round-robin, fair-share, or priority-based, to distribute the resources among the virtual machines according to their needs and preferences. All processes created within the virtual machines are not transparently and equally scheduled in the host system for CPU and I/O usage. The hypervisor can use different scheduling policies, such as proportional-share, co-scheduling, or gang scheduling, to schedule the virtual CPUs of the virtual machines on the physical CPUs of the host system. The hypervisor can alsouse different I/O scheduling algorithms, such as deadline, anticipatory, or completely fair queuing, to schedule the I/O requests of the virtual machines on the physical I/O devices of the host system. The hypervisor can also use different resource accounting and monitoring mechanisms, such as cgroups, perf, or sar, to measure and report the resource consumption and performance of the virtual machines. References:

Oracle VM VirtualBox: Features Overview

Resource Management as an Enabling Technology for Virtualization - Oracle

Introduction to virtualization and resource management in IaaS | Cloud Native Computing Foundation

 The correct command to move the libvirt domain web1 from the current host system to the host system host2 is virsh migrate web1 qemu+ssh://host2/system. This command uses the virsh migrate command, which initiates the live migration of a domain to another host1. The first argument is the name of the domain to migrate, which in this case is web1. The second argument is the destination URI, which specifies the connection to the remote host and the hypervisor to use2. In this case, the destination URI is qemu+ssh://host2/system, which means to use the QEMU driver and connect to host2 via SSH, and use the system instance of libvirtd3. The other options are incorrect because they either use invalid commands or arguments, such as node-update, pool-add, patch, or cp, or they do not specify the destination URI correctly. References:

https://balamuruhans.github.io/2019/01/09/kvm-migration-with-libvirt.html

http://libvirt.org/migration.html

The command lxc-checkpoint is used to checkpoint and restore containers. Checkpointing a container means saving the state of the container, including its memory, processes, file descriptors, and network connections, to a file or a directory. Restoring a container means resuming the container from the saved state, as if it was never stopped. Checkpointing and restoring containers can be useful for various purposes, such as live migration, backup, debugging, or snapshotting. The command lxc-checkpoint has the following syntax:

lxc-checkpoint {-n name} {-D path} [-r] [-s] [-v] [-d] [-F]

The options are:

-n name: Specify the name of the container to checkpoint or restore.

-D path: Specify the path to the file or directory where the checkpoint data is dumped or restored.

-r, --restore: Restore the checkpoint for the container, instead of dumping it. This option is incompatible with -s.

-s, --stop: Optionally stop the container after dumping. This option is incompatible with -r.

-v, --verbose: Enable verbose criu logging. Only available when providing -r.

-d, --daemon: Restore the container in the background (this is the default). Only available when providing -r.

-F, --foreground: Restore the container in the foreground. Only available when providing -r.

The command lxc-checkpoint uses the CRIU (Checkpoint/Restore In Userspace) tool to perform the checkpoint and restore operations. CRIU is a software that can freeze a running application (or part of it) and checkpoint it to a hard drive as a collection of files. It can then use the files to restore and run the application from the point it was frozen at1.

The other statements about the command lxc-checkpoint are not correct. It does not create a clone or an image of a container, nor does it double the memory consumptionof the container. It can work on both running and stopped containers, depending on the options provided. References:

Linux Containers - LXC - Manpages - lxc-checkpoint.12

lxc-checkpoint(1) - Linux manual page - man7.org3

CRIU4

Libvirt uses XML files to store configuration data for objects in the libvirt API, such as domains, networks, storage, etc. This allows for ease of extension in future releases and validation of documents prior to usage. Libvirt does not use any of the other file formats listed in the question. References:

libvirt: XML Format

LPIC-3 Virtualization and Containerization: Topic 305.1: Virtualization Concepts and Theory

The output of xl list shows the state of the domains. The domain with ID 6, Ubuntu, has a state of “b—”. This means that the domain is blocked, which means it is idle or waiting for I/O.

https://xenbits.xen.org/docs/unstable/man/xl.1.html

 A Pod in Kubernetes is a collection of one or more containers that share the same network and storage resources, and a specification for how to run the containers. A Pod is the smallest unit of workload Kubernetes can run, meaning that it cannot be divided into smaller units. Therefore, option C is correct. All containers of a Pod run on the same node, which is the smallest unit of computing hardware in Kubernetes. A node is a physical or virtual machine that hosts one or more Pods. Therefore, option A is also correct. Pods are not always created automatically and cannot be explicitly configured. Pods can be created manually using YAML or JSON files, or using commands like kubectl run or kubectl create. Pods can also be created automatically by higher-level controllers, such as Deployment, ReplicaSet, or StatefulSet. Therefore, option B is incorrect. When a Pod fails, Kubernetes does not restart the Pod on another node by default. Pods are ephemeral by nature, meaning that they can be terminated or deleted at any time. If a Pod is managed by a controller, the controller will create a new Pod to replace the failed one, but it may not be on the same node. Therefore, option D is incorrect. systemd is not used to manage individual Pods on the Kubernetes nodes. systemd is a system and service manager for Linux operating systems that can start and stop services, such as docker or kubelet. However, systemd does not interact with Podsdirectly. Pods are managed by the kubelet service, which is an agent that runs on each node and communicates with the Kubernetes control plane. Therefore, option E is incorrect. References:

Pods | Kubernetes

What is a Kubernetes pod? - Red Hat

What’s the difference between a pod, a cluster, and a container?

What are Kubernetes Pods? | VMware Glossary

Kubernetes Node Vs. Pod Vs.Cluster: Key Differences - CloudZero

 cloud-init uses the /var/lib/cloud/ directory to store status information and configuration information retrieved from external sources, such as the cloud platform’smetadata service or user data files. The directory contains subdirectories for different types of data, such as instance, data, handlers, scripts, and sem. The instance subdirectory contains information specific to the current instance, such as the instance ID, the user data, and the cloud-init configuration. The data subdirectory contains information about the data sources that cloud-init detected and used. The handlers subdirectory contains information about the handlers that cloud-init executed. The scripts subdirectory contains scripts that cloud-init runs at different stages of the boot process, such as per-instance, per-boot, per-once, and vendor. The sem subdirectory contains semaphore files that cloud-init uses to track the execution status of different modules and stages. References:

Configuring and managing cloud-init for RHEL 8 - Red Hat Customer Portal

vsphere - what is the linux file location where the cloud-init user …