Linux Common Boot Issues And Troubleshooting

Explore Red Hat Enterprise Linux 7, its commercial support model and trademark restrictions, and compare it with Fedora. Learn hardware compatibility and the 7.0 to 7.5 release timeline.

Explore systemd as the first process, its on-demand, dependency-based startup that speeds boot time, and the centralized logging that captures and provides access to boot messages.

Explore systemd features that enable parallel boot with dependencies, use cgroups to manage service components, and activate units by sockets, timers, or hardware events.

Compare RHEL 7 and RHEL 6 by examining default file systems, kernel versions, init system changes to systemd targets, and host name and user id range differences for troubleshooting.

Compare rhel7 and rhel6 file systems, boot checks, lvm resize workflows, including 500 terabyte limits and 16 terabyte file system references, with systemd replacing SysV init for service management.

Compare RHEL7 and RHEL6 networking and system changes, covering bonding versus team driver, ifcfg differences, and chrony time synchronization plus structured temporary file management.

Practice session demonstrates using systemctl to check service status, start and stop processes, and enable or disable services for boot behavior, including symbolic links in multi-user.target.

Identify the default target and troubleshoot boot by exploring systemd targets, listing dependencies and units with systemctl, and starting services for graphical or multi-user modes.

Practice lab session analyzes Linux boot performance using systemd-analyze blame and critical-chain, and inspects boot logs with journalctl to troubleshoot boot issues.

Learn how to boot Linux into rescue mode to repair boot issues, using grub menu or kernel line edits, equivalent to single-user mode, requiring a root password.

learn to enter Linux rescue mode using grub menu or boot line edits, set the systemd unit to rescue.target, mount local file systems, and perform maintenance as root.

Learn to use rescue mode and emergency mode to troubleshoot boot failures, enter emergency mode with root password when rescue mode fails, and perform repairs in a minimal environment.

Boot a Linux system into emergency mode by editing the grub line to add systemd.unit=emergency.target, then boot with ctrl-x, log in, and compare the read-only root with rescue mode.

Boot Linux into troubleshooting mode using rescue and emergency modes with media and BIOS, then access a shell to reset passwords and repair missing files.

Learn how to recover a root password in RHEL7 by booting with installation media, entering rescue or troubleshooting mode, mounting the filesystem, and resetting the password.

Reset the root password in RHEL7 by booting from USB media, editing the GRUB line to enter single-user mode, mounting the root filesystem, and running passwd.

Explore grub, the god unified bootloader, and how bios, post, and the mbr hand control to stage 1 and stage 2 bootloaders to load the kernel and init system.

Explain how grub.cfg is the generated bootloader configuration produced by grub-mkconfig from primary configuration files and the grub default. Avoid editing grub.cfg manually and learn how kernel entries are ordered.

Learn grub2 features that make grub an OS-independent bootloader with multiboot support, interactive prompts, and access to file systems including LVM, enabling kernel selection and troubleshooting.

practice lab session shows how to access the grub menu, boot into rescue or emergency modes, and select a previous kernel version for troubleshooting.

Navigate grub boot with lvm integration, select linux 16 and initramfs, and define the root file system to demonstrate boot configuration in this practice lab session.

Edit grub default file to add boot parameters, generate the grub configuration, and test boot changes in a practice lab for linux boot troubleshooting.

Protect Grub with a password to prevent access to single-user mode and the grub console. Learn to generate an encrypted password and update the grub configuration.

Understand how physical RAM is divided into pages, managed by the kernel, and how virtual memory uses swap to free memory when RAM fills, moving inactive pages.

Increase swap space in Linux by creating a new partition and configuring it as swap to boost virtual memory, then enable and make it permanent.

Increase Linux swap space by creating and enabling a swap file when no swap partition is available. Use commands like free, dd, mkswap, swapon, and update fstab for persistence.

Concludes the Linux common boot issues and troubleshooting course with the last lecture, inviting questions and answers and promising ongoing updates with new topics and lectures.