Virtualization

Concept : Identifying Red Hat Virtualization Tools.
Description: Available Red Hat Virtualization tools on a RHEL host, includes the command-line and graphical utilities.
Purpose: Ensure proper virtualization software is installed and discover available management commands.
Linux commands:
yum list installed *kvm* : Lists all installed packages containing "kvm" in their name; 
                           useful to verify KVM and QEMU components.
yum list installed *virt* : Lists all installed packages related to virtualization (like virt-viewer).
virt<TAB><TAB> : Tab completion to list all commands beginning with virt, virt-install, virt-viewer.
man virt-install : Opens the manual for virt-install to understand command syntax and options.
virsh : Command-line shell for managing virtual machines.
man virsh : Opens manual for virsh command, explaining domain management, snapshots, and other VM operations.
Additional Info: 
-Graphical tool Virtual Machine Manager can also list all virtual machines and manage them. 
 This is typically found in Applications -> System Tools.

Concept : Configuring Red Hat Virtualization Tools
Description: Shows configuring Virtual Machine Manager GUI and using virsh shell for managing VMs.
Purpose: Customize virtualization settings for efficient VM management.
Linux commands:
virsh help | more : Lists all available virsh commands with paging.
man virsh : Provides detailed help on virsh commands and options.
gedit /etc/libvirt/qemu/qemu.conf : Opens the configuration file for libvirtd daemon to modify VNC, 
                                    graphics, or SELinux options.
service libvirtd status : Checks if the virtualization daemon is running.
Additional Info: 
-GUI preferences include polling interval, graphics type, USB redirection, and storage format. 
-Command line provides detailed VM lifecycle control.

Concept : Using RHEL 7 as a Virtualized Guest
Description: Demonstrates how to interact with a running VM guest via CLI and GUI.
Purpose: Access, monitor, and manage VMs from host.
Linux commands:
virsh list : Lists running VMs.
virsh dominfo <vm-name> : Shows domain info: state, CPUs, RAM, autostart, etc.
virsh snapshot-create <vm-name> : Creates a snapshot of a running VM.
virsh console <vm-name> : Connects to VM console from host terminal. Use Ctrl+] to exit.
fdisk -l /dev/sdb : Shows partitions on a redirected USB device.
mount /dev/sdb1 /mnt : Mounts USB device for access inside VM.
ls /mnt : Lists contents of mounted device.
Additional Info: 
-GUI Virtual Machine Manager also allows console access, snapshot management, 
 USB redirection, display scaling, and VM operations like pause, shutdown, or reboot.

Concept : Installing RHEL 7 as a Virtualization Guest
Description: Shows creating a VM using virt-install or the graphical Virtual Machine Manager.
Purpose: Deploy a new RHEL 7 guest VM.
Linux commands:
man virt-install : Displays options for specifying RAM, CPUs, disk image, boot media, network, and installation source.
virt-install --name rhel7.0 --ram 2048 --vcpus 2 --disk path=/var/lib/libvirt/images/rhel7.0.qcow2,size=8 
             --cdrom /path/to/rhel7.iso --network network=default : Creates a VM from ISO with specified configuration.
GUI alternative: Applications → System Tools → Virtual Machine Manager → File → New Virtual Machine → follow wizard.
Additional Info: 
-VM creation GUI allows setting RAM, CPU, storage, networking, and MAC address. 
-Installation behaves like physical host installation.

Concept : Launching RHEL 7 as a Guest
Description: Demonstrates starting VMs via GUI or CLI.
Purpose: Power on virtual machines and connect to console immediately.
Linux commands:
virsh start rhel7.0 --console --force-boot : Starts VM and attaches console, forcing a fresh boot.
GUI method: Applications -> System Tools -> Virtual Machine Manager -> select VM -> Play or Run.
Additional Info: 
-Console allows viewing startup messages directly from host. 
-GUI shows VM state updates in real-time.

Concept : Configuring a RHEL 7 Guest
Description: Configure VM hardware via GUI or command line (virsh).
Purpose: Modify memory, CPUs, NICs, and other virtual hardware for a VM.
Linux commands:
virsh list --all : List all guests.
virsh dominfo <vm-name> : Shows current VM configuration.
virsh setmem <vm-name> --size 1G : Sets memory allocation for the VM.
virsh edit <vm-name> : Opens XML config to modify VM hardware or settings.
Additional Info: 
-GUI: Virtual Machine Manager -> View -> Details allows changing CPU, memory, 
      NIC model (virtio for performance), and applying changes.

Concept : Configuring International Keyboards
Description: Configures language and keyboard layout in GUI and CLI.
Purpose: Support multiple languages for host and guest systems.
Linux commands:
localectl status : Shows current language and keyboard configuration.
localectl list-keymaps | grep french : Lists French keyboard layouts.
localectl set-x11-keymap cm-french : Sets graphical X11 keyboard layout.
localectl set-keymap cm-french : Sets console keymap.
Additional Info: 
-GUI: Applications -> System Tools -> Settings -> Keyboard -> Typing -> Input Sources -> Select language.

Concept : Detecting Problems in a Guest
Description: Configure pvpanic to report VM panic events.
Purpose: Enable VM crash detection and management.
Linux commands:
virsh list --all : Lists VMs.
virsh edit <vm-name> : Modify XML to add <panic> element in <devices> section.
Additional Info: 
-GUI: Virtual Machine Manager -> View -> Details -> Panic Notifier shows configured ISA address for pvpanic.

Concept : Using sVirt to Protect Guests
Description: Explains SELinux integration (sVirt) to isolate VMs.
Purpose: Prevent one compromised VM from affecting others or the host.
Linux commands:
getenforce : Check SELinux mode (Enforcing, Permissive, Disabled).
virsh dumpxml <vm-name> | grep label : Shows security label of VM.
ls -laZ <disk-file> : Shows SELinux security label of VM disk.
Additional Info: 
-Dynamic labeling by default ensures VMs and disk files are isolated. 
-Useful for multi-tenant virtualization.

Concept : Using RHEL 7 as a Virtualization Host
Description: Considerations for hosting multiple VMs.
Purpose: Optimize hardware and host configuration for multiple concurrent guests.
Linux commands:
No specific commands; mainly system planning.
Additional Info: 
-Consider RAM, CPU cores, disk, BIOS virtualization settings (VT-x/AMD-V), NICs, SR-IOV, 
 PCI passthrough, clustering, and storage locations.

Concept : Configuring RHEL 7 Host Settings
Description: Shows host networking, virtual bridges, and VM networking configuration.
Purpose: Ensure proper connectivity and virtual networking for guests.
Linux commands:
yum list installed *qemu* : Verify installed virtualization packages.
ifconfig : Display network interfaces, including virbr0 and vnetX.
virsh net-list --all : Show virtual networks.
virsh net-dumpxml default : Display virtual network XML configuration.
brctl show : Show bridge interfaces and connected VMs.
virsh dumpxml <vm-name> | grep network : Check VM network configuration in XML.
Additional Info: 
-Virtual bridges (virbr0) enable NAT for guest VMs; vnet interfaces correspond to active VMs.

Concept : Creating and Managing Virtual Machines
Description: How to create, configure, snapshot, and clone VMs.
Purpose: Deploy new VMs and manage existing VMs effectively.
Linux commands:
virt-install : Create VM with parameters for RAM, CPUs, disk, network, and install source.
virsh list --all : List all VMs, running or stopped.
virsh dumpxml <vm-name> : View XML configuration of a VM.
virsh edit <vm-name> : Modify VM configuration via XML.
virsh dominfo <vm-name> : Get basic VM info.
virsh setmem <vm-name> --size <size> : Adjust VM memory allocation.
virsh snapshot-create <vm-name> : Create a snapshot for backup or testing.
Additional Info: 
-GUI: Virtual Machine Manager allows snapshots, cloning, pause, shutdown, and migration.

Concept : Accessing a Virtual Machine Console
Description: Access VM console via CLI, VNC, or SSH.
Purpose: Monitor VM activity and interact with the guest system.
Linux commands:virsh list : Shows active VMs.
virsh console <vm-name> : Connects directly to VM console; exit via Ctrl+].
virsh domdisplay <vm-name> : Shows available VNC session.
vncviewer localhost:1 : Connect to VM console via VNC.
virsh dumpxml <vm-name> | grep graphic : Verify VM VNC configuration in XML.
virsh edit <vm-name> : Modify XML for VNC support.
ssh root@<vm-ip> : Connect to VM via SSH.
Additional Info: 
-Console access allows embedded command-line interaction similar to being directly logged into the guest OS.

Concept: Starting and Stopping a Virtual Machine Guest
Description: Demonstrate how to list, start, and stop virtual machine guests on a 
             Linux host using both the command line (virsh) and graphical Virtual Machine Manager.
Purpose: To manage virtual machines’ power state efficiently and understand graceful vs forced shutdowns.
Linux commands:
virsh list --all : Lists all virtual machines on the host, including those that are powered off. Shows their IDs, names, and states.
virsh start <guest_name> : Starts a virtual machine with the specified name. This is equivalent to "Power On" in the GUI.
virsh shutdown <guest_name> : Gracefully shuts down the virtual machine. Uses the guest OS shutdown procedure.
virsh destroy <guest_name> : Forces the virtual machine off immediately. Not graceful; should be used only if shutdown hangs.
virsh list : Lists currently running virtual machines with assigned IDs.
Additional Info:
-The graphical Virtual Machine Manager provides a visual CPU usage chart for each guest.
-Force options like destroy or "Force Off" bypass guest OS operations and should be used cautiously.
-Virtual machines may require user input during shutdown or reboot, depending on OS configuration.

Concept: Configuring Guests to Autostart
Description: How to configure a virtual machine to start automatically 
             when the host boots, both via GUI and command line.
Purpose: To ensure critical virtual machines are available immediately after host boot without manual intervention.
Linux commands:
virsh list : Lists all virtual machines with their current state.
virsh autostart <guest_name> : Marks a virtual machine to start automatically at host boot.
virsh autostart --disable <guest_name> : Disables autostart for the specified virtual machine.
virsh dominfo <guest_name> : Provides detailed information about a virtual machine, including 
                             autostart status, state, ID, CPUs, and memory.
Additional Info:
-The GUI Virtual Machine Manager provides an "Autostart" checkbox under Boot Options.
-Autostart status can be verified with dominfo, showing Autostart: enabled/disabled.
-Autostart can simplify server management in production environments.

Concept: Obtaining Guest Information
Description: How to retrieve information about virtual machine guests 
             using GUI tools and the virsh command line.
Purpose: To inspect guest configuration, resource usage, and state to monitor and manage virtual machines effectively.
Linux commands:
virsh domstate <guest_name> : Displays the current state of a guest (running, paused, shut off).
virsh dominfo <guest_name> : Shows detailed information including ID, UUID, memory, CPU count, and autostart status.
virsh vcpuinfo <guest_name> : Lists virtual CPU configuration of the guest.
virsh domiflist <guest_name> : Lists network interfaces attached to the guest.
virsh screenshot <guest_name> : Captures a screenshot of the running guest’s display.
virsh dumpxml <guest_name> | more : Outputs the entire XML configuration of the guest, 
                                    showing all hardware and software settings.
Additional Info:
-GUI tools show CPU usage and provide access to the guest console for direct login.
-The XML dump can be used to replicate or backup VM configurations.
-The information retrieved helps in troubleshooting performance or configuration issues.

Concept: Throttling Guest I/O and Managing Performance
Description: Monitor virtual machine performance and tuning disk I/O to prevent one VM 
             from degrading host or other VMs’ performance.
Purpose: To optimize resource allocation and prevent performance bottlenecks in a virtualized environment.
Linux commands:
virt-top : Similar to top, but displays running virtual machines with resource usage stats (CPU, memory).
virsh dominfo <guest_name> : Provides CPU, memory, and basic info of a guest.
virsh cpu-stats <guest_name> : Displays CPU usage per virtual CPU and total CPU consumption.
man virsh : Accesses the manual for virsh, useful to find options like blkdeviotune.
virsh blkdeviotune <guest_name> --path /dev/vda --total-bytes-sec 10485760 : Example of setting I/O limits (total bytes/sec) for a virtual disk.
Additional Info:
-Graphical Virtual Machine Manager allows monitoring of CPU, memory, disk, and network usage.
-Disk I/O is a major contributor to host performance degradation; tuning it ensures fair resource allocation.
-CPU stats and I/O limits can be adjusted dynamically without shutting down the guest.

Concept: Setting Up a Virtualization Host and Installing Guests via Kickstart
Description: Preparing a host for virtualization, creating a kickstart script, and installing a 
             guest OS automatically with resource management.
Purpose: To automate guest installation, verify host readiness, and configure resource limits for virtual machines.
Linux commands:
yum list installed | grep qemu : Checks if virtualization packages like QEMU are installed.
yum install qemu-kvm libvirt virt-install : Installs necessary packages if missing.
cat /proc/meminfo : Verifies available RAM on the host.
ifconfig : Checks network connectivity for guest communication.
virt-install --name rhel7.0 --ram 2048 --disk path=/var/lib/libvirt/images/rhel7.0.qcow2,size=20 --vcpus 2 
             --os-variant rhel7.0 --graphics vnc --cdrom /path/to/iso --extra-args "ks=http://server/ks.txt" 
             : Installs a virtual machine using a kickstart file, with specified CPU, RAM, disk, and VNC graphics.
GUI Virtual Machine Manager can also start, monitor, and configure performance for the guest after installation.
Additional Info:
-Kickstart files automate OS installation by specifying root password, disk partitioning, network, 
 software packages, and scripts.
-Web-hosted kickstart files allow network-based installation.
-IO tuning for virtual disks can be applied in GUI or via virsh blkdeviotune for consistent guest performance.