Red Hat System Administration I
Build virtual system components and install Red Hat Enterprise Linux into KVM virtual machines.
Objectives
After completing this section, students should be able to:
Build a virtual machine configuration.
Install Red Hat Enterprise Linux into a new virtual machine instance.
Creating a virtual machine
Virtual machines can perform the same tasks as physical systems. System administrators make system sizing and configuration decisions using fundamentally the same criteria as for physical systems, including the guest machine's role and projected system load. Preparatory considerations must include CPU and memory requirements, type of I/O and the expected number of clients, access to public or exclusive storage, current and future sizing expectations, and bandwidth and latency requirements. Necessary disk and network components must be configured on the virtual host before creating the guest.
Launch the Virtual Machine Manager from the menu → → , or run the virt-manager command as root. Click the button to open the New VM wizard. Ensure that virt-manager can access the installation media (whether locally or over the network) before continuing.
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Select a name for the virtual machine, which is used as the configuration domain name. The system host name is configured later during the operating system installation. Choices for installation type depend on what resources are prepared. An operating system DVD must be available on the virtual host or on physical media before selecting Local install media, for example, or a network installation server must be available when selecting Network Boot (PXE). Sharing and accessing the installation media using any file sharing protocol is chosen here.
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Enter the URL for the installation media network resource. Configure an appropriate OS type and Version for this guest. When the installation media is currently accessible, selecting Automatically detect operating system fills these fields. If the fields remain blank or are incorrect, fix the installation media before continuing. The Kickstart options allow unattended installations; a Kickstart server and preconfigured client configuration file are required.
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Configure an appropriate amount of Memory and CPUs. Red Hat Enterprise Linux 7 requires a minimum of one CPU and 1024MB of memory.
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Assign storage to the guest virtual machine. For a created disk image, allocating now will provide a small performance benefit, while allocating later saves disk space not yet needed. To Select managed or other existing storage requires having previously prepared a disk image, physical device, or logical volume prior to beginning this install.
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Verify the settings of the virtual machine in the top half of the dialog window. Open the Advanced options to configure networking. Virtual machines can be configured as private guests using Network Address Translation (NAT), or given the appearance of direct subnet access by using the virtual host's preconfigured bridge.
The New VM wizard automatically generates a MAC address in the 52:54:00 range for virtual guests. Use the random MAC provided or replace the address with one that fits the environment requirements. Unless the Customize configuration before install checkbox is selected, the virtual machine creation will begin when the button is pressed.
Note
In production environments, DNS and DHCP databases are preconfigured with host names and reserved IP addresses assigned to registered MAC addresses so as to centralize and coordinate enterprise-wide virtual system management. In a Red Hat Training environment, the classroom DNS server has been populated with MAC addresses and unique names for anticipated student guest systems. Use an appropriate MAC address as directed by the instructor or exercise instructions.
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If the Customize configuration before install
checkbox was selected on the last step of the New VM wizard,
the domain_name Virtual Machine detail screen displays.
Administrators can further modify or correct the configuration before the installation begins.
Additional hardware—such as graphics and other add-in cards,
disks, and network interfaces—may be configured here.
When customization is complete, press Begin Installation in the upper-left corner.
When the installation is complete, administrators can return to this same detail screen to modify or correct the virtual machine configuration. The option for automatically starting this virtual machine when the physical host boots is also found here.
Installing Red Hat Enterprise Linux
It is recommended that Red Hat Enterprise Linux be installed using the graphical interface, known as anaconda. If anaconda detects that an installation started in text mode where a VNC connection might be possible, anaconda asks to verify. The text mode installation is simpler, but certain options available in graphical mode are not available in text mode.
During a RHEL7 installation, on a physical machine, two virtual consoles are provided. The first virtual console has five windows provided by the tmux software terminal multiplexer. The second virtual console is used to display the graphical interface of anaconda. Multiple tmux windows in the first virtual console are used to provide information such as diagnostic messages and the ability to enter commands from a shell prompt.
The following table lists the virtual consoles, tmux windows, and keystrokes used to switch between them during an installation. The keyboard shortcuts are performed in two actions. Press Ctrl+b and while releasing those keys press the number key of the window you want to access.
Table 15.1. Description of virtual consoles
Console | Keyboard shortcut | Contents |
|---|---|---|
| 1 | Ctrl+Alt+F1 | Main installer console, uses the tmux windows for text installation and anaconda logs |
| 2 | Ctrl+b 1 | The main tmux window for anaconda, displays either the text installer if opted or displays the general command debug or warning outputs of the GUI interface of the running installer |
| 3 | Ctrl+b 2 | Shell prompt with root access |
| 4 | Ctrl+b 3 | Installation log, displays messages stored in |
| 5 | Ctrl+b 4 | Storage log, displays messages on related storage devices from kernel
and system services, stored in |
6 | Ctrl+b 5 | Program log, displays messages from other system utilities,
stored in |
| 7 | Ctrl+Alt+F6 | The default console with GUI interface of the installer |
Note
The above reference table is in line with the RHEL7 releases. However, there may be other active virtual consoles accessible between Ctrl+Alt+F2 and Ctrl+Alt+F5 but are for legacy compatibility only.
At the Welcome to Red Hat Enterprise Linux 7.0 screen, select the language to be used during installation. After install, users select their own preferred language upon new account login.
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The anaconda Installation Summary screen displays. From this central screen, installation customizations may be provided before beginning the installation. The installer allows configuring the installation items in any order. Select an item to view or edit. When an item is completed, or it is intended to be completed later, press to return to this central screen.
Only items marked with a warning symbol are mandatory. The orange status bar at the bottom of the screen warns that these items must be completed before the installation can begin. Once required items are complete, press the button. Pressing the button aborts the installation. The virtual machine configuration will remain, but be unbootable until an operating system installation is restarted and completed.
As required, complete the following items:
Date and time - Select your city by clicking in the interactive map or select from the dropdown list. Specify a time zone even when using Network Time Protocol (NTP). Messages complaining that NTP is not configured may be ignored if no NTP servers are available.
Language support - Select languages to install in addition to the default language already specified. Multiple languages and locales may be selected.
Keyboard - This item allows adding additional keyboard layouts beyond that included with your default language.
Installation source - The installation source was selected during the virtual machine creation steps and should not need to be modified.
Software selection - By default, the graphical installer selects the Minimal install environment, providing only packages essential to run Red Hat Enterprise Linux. In Software Selection, choose from a list of other base environments by clicking the radio button for an available environment listed in the left pane. Next, select Add-Ons for the selected environment from the checkboxes in the right pane.
Installation destination - Select and partition the disks onto which Red Hat Enterprise Linux will install. This item expects an administrator to comprehend partitioning schemes and file system selection criteria. The default radio button for automatic partitioning will allocate the selected storage devices using all available space. If there are no other operating systems already installed on this computer or you have chosen not to preserve a previously installed operating systems, anaconda automatically installs GRUB2 as the boot loader.
Network & host name - Detected network connections are listed in the left pane. Click a listed connection to display more details. To configure a network connection manually, click the button in the lower-right corner. A dialog appears to configure the selected connection. Configuration options depend on available network hardware. Only network connections required for installation must be configured here.
When installation customization is complete, press .
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The anaconda Configuration screen displays. The installation has already started; Red Hat Enterprise Linux reports progress near the bottom of the screen as it installs selected packages to the system.
As required, complete the following items:
Root password - The installation program prompts to set a root password for the system. The final stage of the installation process will not continue until a root password is entered.
User creation - Use the root account only for system administration. Create a non-root account for general use. Though recommended to do during installation, this step is optional and can be performed after the installation is complete.
When the installation states that it is complete, press . After the virtual machine's normal power-up sequence has completed, Red Hat Enterprise Linux loads and starts, hidden behind a graphical screen that displays a progress bar. If a graphical desktop was installed, the GUI login displays. Log in as the user created during installation, or as root. The anaconda Initial Setup screen displays.
As required, complete the following items:
License information - The installation program prompts to accept the licensing terms.
User creation - Displays only if a non-root account has not yet been created.
When initial setup tasks are complete, press . The FirstBoot utility displays, prompting entry of the final configuration information for this system. Use this utility to:
Configure the Kdump crash dump mechanism.
Set the system time and date.
Register the machine with Red Hat Network through Subscription Management.
The Red Hat Enterprise Linux installation is now complete. The system is ready for normal login and use.
References
Additional information for the guest VM creation may be available in the section on creating guests with virt-manager in the Red Hat Enterprise Linux Virtualization Deployment and Administration Guide for Red Hat Enterprise Linux 7, which can be found at https://access.redhat.com/documentation/
virt-manager(1) man page
Additional information for reference of the installation environment is available in the section on installation and booting in the Release Notes for Red Hat Enterprise Linux 7, which can be found at https://access.redhat.com/documentation/
