


Open source load balancing LVS random self-start exception diagnosis case analysis_PHP tutorial
Open source load balancing LVS random self-start abnormal diagnosis case analysis
In response to the country’s call to advocate the security, autonomy and controllability of IT information system software and hardware facilities, our company also Efforts are being made to promote the localization and open source of IT software and hardware. Therefore, the open source load balancing software LVS was introduced and multiple LVS systems were deployed in production. A strange problem was discovered during use. After configuring random auto-start, some LVS systems can start normally with the server when the operating system is restarted. However, one of the systems cannot start the service automatically with the operating system. In order to solve this problem, the following is provided.1. Problem phenomenon
The specific symptoms of this set of LVS failures are as follows:
LVS has been configured as a system service normally and set to 2345 to start automatically at boot. However, after restarting the server, it was found that the service did not start as expected. By checking the system's diagnostic log tail –f /var/log/messages, we found that ipvs frequently flushes logs to the messages file.
The specific error message is as follows: Keepalived_healthcheckers: IPVS: Can't initialize ipvs: Protocol not available. After manually executing ipvsadm -Ln, the service returns to normal.
2. Analysis process:
1. Through the diagnostic log prompts, we can confirm that the root cause of the problem is that the ipvs module was not loaded normally when the system restarted
2. By executing the following command lsmod|grep ip_vs It also further confirms that the corresponding module is not loaded into the kernel
So what is the reason why the ipvs module is not loaded into the Linux kernel?
3. Debug specific ideas:
1. Test the settings and restart without starting keepalived. Only start ipvsadm to see if it can be started. The problem remains after restarting, indicating that the problem is not with keepalived for the time being;
2. Replace high I changed the version of ipvsadm to 1.25 and the problem remained after the test;
3. I began to suspect that the installation sequence was the reason, so I tested both versions of ipvsadm in a different installation sequence than keepalived, and matched the startup sequence, but the problem remained;
4. Accidentally use the /etc/init.d/ipvsadm start command to start the ipvs service and then restart the operating system. ipvsadm is successfully pulled up by the system and the snapshot is saved immediately.
5. So I checked the startup script of ipvsadm. The script is relatively cumbersome and involves many files. I found a configuration file /etc/sysconfig/ipvsadm. Suddenly I got an idea, is there something wrong with the configuration file? After searching for the ipvsadm file, the problem was found. There is one missing configuration file under /etc/sysconfig;
6. Manually create the ipvsadm configuration file touch ipvsadm, and then restart the system. The ipvsadm service started successfully
4. Best solution Solution
After deploying and configuring LVS, execute the service ipvsadm save command
5. Cause of this problem
The relevant deployment personnel did not follow the deployment manual and missed relevant steps, which resulted in the random self-starting of ipvs. related configuration files.

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

WebStorm Mac version
Useful JavaScript development tools

Atom editor mac version download
The most popular open source editor

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software