Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

By : Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty
2 (2)
Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

2 (2)
By: Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty

Overview of this book

With Red Hat Enterprise Linux 9 becoming the standard for enterprise Linux used from data centers to the cloud, Linux administration skills are in high demand. With this book, you’ll learn how to deploy, access, tweak, and improve enterprise services on any system on any cloud running Red Hat Enterprise Linux 9. Throughout the book, you’ll get to grips with essential tasks such as configuring and maintaining systems, including software installation, updates, and core services. You’ll also understand how to configure the local storage using partitions and logical volumes, as well as assign and deduplicate storage. You’ll learn how to deploy systems while also making them secure and reliable. This book provides a base for users who plan to become full-time Linux system administrators by presenting key command-line concepts and enterprise-level tools, along with essential tools for handling files, directories, command-line environments, and documentation for creating simple shell scripts or running commands. With the help of command line examples and practical tips, you’ll learn by doing and save yourself a lot of time. By the end of the book, you’ll have gained the confidence to manage the filesystem, users, storage, network connectivity, security, and software in RHEL 9 systems on any footprint.
Table of Contents (26 chapters)
1
Part 1 – Systems Administration – Software, User, Network, and Services Management
9
Part 2 – Security with SSH, SELinux, a Firewall, and System Permissions
14
Part 3 – Resource Administration – Storage, Boot Process, Tuning, and Containers
21
Part 4 – Practical Exercises

Preparing systems to use VDO

As mentioned earlier, VDO is a driver, specifically a Linux device-mapper driver, that uses two kernel modules:

  • kvdo: This does data compression.
  • uds: This is in charge of deduplication.

Regular storage devices such as local disks, Redundant Array of Inexpensive Disks (RAIDs), and so on are the final backend where data is stored; the VDO layer on top reduces disk usage via the following:

  • The removal of zeroed blocks, only storing them in the metadata.
  • Deduplication: Duplicate data blocks are referenced in the metadata but stored only once.
  • Compression, using 4 KB data blocks with a lossless compression algorithm (LZ4: https://lz4.github.io/lz4/).

These techniques have been used in the past in other solutions, such as in thin-provisioned VMs that only kept the differences between VMs, but VDO makes this happen transparently.

Similar to thin-provisioning, VDO can mean faster data throughput, as data can be cached...