Administration Section
Hello everyone! In this article, we will migrate the GitLab database from the internal PostgreSQL, which is installed along with GitLab, to an external PostgreSQL that is already set up on another server. NOTE: All actions are guaranteed to work on CentOS 7.7.1908, PostgreSQL 12, and GitLab 12.4.2-ee.0. Preliminary Preparation: Let's complete three actions in advance: 1. On the PostgreSQL server, add a rule in the firewall to allow incoming […]
We continue our series of materials dedicated to server performance testing. Today we'll discuss a couple of time-tested benchmarks that are still maintained and updated — NetPerf, HardInfo, and ApacheBench. Photo — Peter Balcerzak — CC BY-SA NetPerf This is a tool for assessing network bandwidth. It was developed by engineers from Hewlett-Packard. The tool includes two executable files: netserver and […]
Introduction I wanted to study a mail server for a long time, but I only managed to find the time now, and there wasn't much accurate information available, so I decided to write as detailed a publication as possible. This publication will cover not only postfix, dovecot, mysql, and postfixadmin, but also spamassassin, clamav-milter (a special version of clamav for mail servers), postgrey, and […]
We have designed a data center network that allows deploying compute clusters larger than 100,000 servers with a peak bisection bandwidth of over one petabyte per second. From Dmitry Afanasyev's report, you will learn about the fundamental principles of the new design, the scaling of topologies, the issues that arise, possible solutions, the peculiarities of routing, and the scaling of the forwarding plane features of modern […]
Disclaimer: I am a developer. I write code and interact with the database only as a user. I do not claim to be a system administrator or DBA in any way. However... It turned out that I needed to organize a backup of a PostgreSQL database. No clouds — just use SSH and make sure everything works without asking […]
Hello, friends! Today, I will continue the series dedicated to Extreme switches with an article on Enterprise network design. In this article, I will try to be as brief as possible: describe the modular approach to designing an Enterprise network, examine the types of building one of the most important modules of the enterprise network — the backbone network (IP campus), describe the advantages and disadvantages of options for redundantly protecting critical network nodes using an abstract example, design/update […]
The former coal mine, which will house the Arctic World Archive storage. Photo: Guy Martin / Bloomberg Businessweek Free software is the cornerstone of modern civilization and a shared heritage of all humanity. The mission of the GitHub Archive program is to preserve this code for future generations, ensuring that the history of the Library of Alexandria never repeats itself. To this end, GitHub will maintain multiple backups in various […]
Introduction: An I/O reactor (single-threaded event loop) is a pattern for writing high-load software used in many popular solutions: Node.js, Tor, Transmission, Chromium, Memcached, etc. In this article, we will explore the underpinnings of the I/O reactor and the principle of its operation, implement it in less than 200 lines of code, and make a simple HTTP server handle over 40 million requests per minute. Preface […]
I wrote this review (or, if you prefer, a comparison guide) when I was asked to compare several devices from different vendors. Moreover, these devices belonged to different classes. I had to delve into the architecture and specifications of all these devices and create a 'coordinate system' for comparison. I hope my review helps someone: To understand the descriptions […]
The Near Future Several methods are used by facial recognition systems, but generally, it refers to technology capable of identifying a person through a digital image or a frame from a video source. Many smartphone owners use face recognition daily, but in mobile devices, recognition speed is not critical, and the number of users rarely exceeds one or two. For office and outdoor […]
Introduction The HR department of a manufacturing company asked what a system administrator should do? For organizations with a single IT specialist on staff, this question has a catch. I tried to describe the functional levels of one specialist in simple terms. I hope this helps someone communicate with non-IT folks. If I missed anything, my senior colleagues will correct me. Level: Technician Tasks. Here, operational issues are addressed. […]
Hello everyone! My name is Dmitry Samsonov, and I work as a lead system administrator at 'Odnoklassniki'. We have over 7,000 physical servers, 11,000 containers in our cloud, and 200 applications that, in various configurations, form 700 different clusters. The overwhelming majority of servers run on CentOS 7. On August 14, 2018, information about the FragmentSmack vulnerability was published […]