CentOS 7 Installation: A Comprehensive Guide
1.1 CentOS Evolution
The CentOS project has undergone significant changes over the years, with three major startup technologies being employed: sysvinit, upstart, and systemd.
1.1.1 Start Process Sysvinit
Sysvinit is a traditional startup technology that starts processes one at a time, resulting in a slow and cumbersome startup process. It relies heavily on shell scripts and can be prone to errors.
Advantages:
- Works well with existing IT infrastructure
- Relies on shell scripts
Disadvantages:
- Slow startup
- Easy to tamp, fstab, and nfs mount problems
1.1.2 Upstart Technology
Upstart is a more modern startup technology that was used in CentOS 6 and Ubuntu 14.04. It overcomes the inherent shortcomings of sysvinit and improves the startup speed of the system.
1.1.3 Systemd Technology
Systemd is the latest startup technology used in CentOS 7. It overcomes the inherent shortcomings of upstart and improves the startup speed of the system.
1.1.4 Comparison of Three Startup Technologies
The three startup technologies differ in their approach to starting processes. Sysvinit starts processes one at a time, while upstart and systemd start processes in parallel.
Three Principles of Parallel Start:
- Resolve socket dependencies
- Solve D-Bus dependency
- Resolve file system dependencies
1.2 Installation System CentOS 7
1.2.1 Virtual Machine Selection
When selecting a virtual machine, it is essential to choose one with as much disk space as possible.
1.2.2 System Installation
The system installation process involves the following steps:
- Boot into the installation
- Pressing TAB to add kernel options
- Selecting the language
- Setting the host name and network connection
- Noting the boot from the start
- Setting the IP address
- Modifying the host name
- Selecting the installation environment
- Checking dependencies
- Disk partitions and custom partitions
1.3 Optimization after Installation
After the installation is complete, it is essential to optimize the system.
The Difference CentOS 7 with CentOS 6
CentOS 7 has several differences from CentOS 6, including:
- Solving the problem after replacing the card name change
- Using nmtui for network management
- Configuring the host distinguished name
- Changing the character set
1.4.1 To Solve the Problem after Replacing the Card Name Change
The method for replacing the card name change in CentOS 7 is different from that in CentOS 6.
1.4.2 nmtui
nmtui is a graphical tool used for network management in CentOS 7.
1.4.3 Host Distinguished Name of the Configuration File
The host distinguished name is configured in the /etc/hostname file.
1.4.4 Character Set
The character set is configured in the /etc/locale.conf file.
1.4.5 Viewing System Version
The system version can be viewed using the command cat /etc/os-release.
1.4.6 Compatible rc.local
The rc.local file is compatible with CentOS 7.
1.4.7 Runlevels
Runlevels are configured using the systemctl command.
1.4.8 Systemd Dominates the World
Systemd is the dominant startup technology in CentOS 7.
1.4.9 Management Services
Management services are disabled using the systemctl command.
1.4.10 Contrast Commands
The contrast command is used to compare the performance of different services.
1.4.11 Boot Time Optimization
Boot time optimization is performed using the systemd-analyze command.
1.4.12 Boot Refinements
Boot refinements are performed using the systemctl command.
1.4.13 Chinese Reference Document
The Chinese reference document is available at Red Hat Enterprise Linux | 7 | Red Hat Documentation.
1.5 Conclusion
In conclusion, CentOS 7 is a powerful and flexible operating system that offers a range of features and tools for system administrators. With its improved startup speed and management services, CentOS 7 is an ideal choice for businesses and organizations.