In this article, you will find a detailed tutorial on data recovery from RAID 0, 1 or 5. The array we have been testing was built on Linux, and the methods described here will help you recover your files even if one or several disks break down.
Data Recovery from LVM Volumes in Linux
Tutorial
Would you like to know how to use the LVM technology in Linux? How to create an LVM volume, how to configure and mount it in your operating system, how to add and remove disks, and how to recover the information you have accidentally deleted? In today’s article, you will find all of that – and even more.
Creating and using your own deb repository (not mirroring)
Tutorial
Tested on the following configuration:
Server: ubuntu 20.04
Clients: ubuntu 16.04, 18.04, 20.04
It doesn’t require a lot of software to create it.
Using kconfig for own projects
Intro
Every Linux professional write scripts. Someеimes light, linear. Sometimes complex script with functions and libs(yes, you can write your bash-library for use in other scripts).
But some of the scripts need a configuration file to work. For instance, I wrote a script that builds the ubuntu image for pxe, and I need to change the build process without build-script changes. The best way to resolve this task is to add configuration files.
Boot Ubuntu via http/ftp server with pxe(diskless boot)
Tutorial
Intro
PXE is a great solution for booting a diskless computer (or a computer without an OS installed). This method is often used for terminal stations and OS mass installation.
Stock ubuntu (16.04) in pxe-mode can mount rootfs only from NFS. But this is not a great idea: any difficulties with the network/NFS server and the user gets problems.
In my opinion, it's best to use other protocols, such as http/ftp. Once booting, you will have an independent system
External Interrupts in the x86 system. Part 2. Linux kernel boot options
Tutorial
In the last part we discussed evolution of the interrupt delivery process from the devices in the x86 system (PIC → APIC → MSI), general theory, and all the necessary terminology.
In this practical part we will look at how to roll back to the use of obsolete methods of interrupt delivery in Linux, and in particular we will look at Linux kernel boot options:
- pci=nomsi
- noapic
- nolapic
Also we will look at the order in which the OS looks for interrupt routing tables (ACPI/MPtable/$PIR) and what the impact is from the following boot options:
- pci=noacpi
- acpi=noirq
- acpi=off
You've probably used some combination of these options when one of the devices in your system hasn't worked correctly because of an interrupt problem. We'll go through these options and find out what they do and how they change the kernel '/proc/interrupts' interface output.
Porting packages to buildroot using the Zabbix example
Tutorial
The basics of porting
Originally, Buildroot offers a limited number of packages. It makes sense — there is everything you need, but any other packages can be added.
To add a package, create 2 description files, an optional checksum file, and add a link to the package in the general package list. There are hooks at different stages of the build. At the same time, Buildroot can recognize the needed type of packages:
How I fix cups-printing in Buildroot
Intro
Like I said earlier in previos articles, Buildroot is a great system for embedded Linux development. But sometimes strange things can happen.
Once upon a workday, I got the following task: add printing system in firmware (Kraftway terminal Linux next generation). Ok, so I had to add cups + cups filter and to build firmware. I set a postscript-printer and got an error "Filter failed". Trivial tasks turned into serious work.
In this article, I wrote my own way of solving this problem. It may be useful for other developers and IT-specialist and, also, for a deeper understanding of the Buildroot.
If you are a Buildroot beginner, I recommend reading my previous articles.
Update 1 may 2020
Revisioned versions of this patches applied to master.
buildroot — my own experience with multi-platform distro creation
Introduction
In my previous article (Monitor linux) I wrote, what is this distro and how it works. Now i will write how to do it. It's may be interesting for everyone, who want to study buildroot.
Target goals
The result we get from article is the following:
- Firmware (non-volatile image with restorable config)
- Easy management via web-interface
- Cross-platform (qemu x86_64, arm-based SBC like rasberry 4, beagle bone black and asus tinker board)
- Support without extra effort
Cool WSL (Windows Subsystem for Linux) tips and tricks
Microsoft corporate blog Configuring Linux *Visual Studio *Development for Linux *Development for Windows *
It's no secret I dig WSL (Windows Subsystem for Linux) and now that WSL2 is available in Windows Insiders Slow it's a great time to really explore the options that are available. What I'm finding is so interesting about WSL and how it relates to the Windows system around it is how you can cleanly move data between worlds. This isn't an experience you can easily have with full virtual machines, and it speaks to the tight integration of Linux and Windows.
Look at all this cool stuff you can do when you mix your peanut butter and chocolate!
Read more →Look at all this cool stuff you can do when you mix your peanut butter and chocolate!
Lessons learned from testing Over 200,000 lines of Infrastructure Code
IaC (Infrastructure as Code) is a modern approach and I believe that infrastructure is code. It means that we should use the same philosophy for infrastructure as for software development. If we are talking that infrastructure is code, then we should reuse practices from development for infrastructure, i.e. unit testing, pair programming, code review. Please, keep in mind this idea while reading the article.
WSL 2 is now available in Windows Insiders
We’re excited to announce starting today you can try the Windows Subsystem for Linux 2 by installing Windows build 18917 in the Insider Fast ring! In this blog post we’ll cover how to get started, the new wsl.exe commands, and some important tips. Full documentation about WSL 2 is available on our docs page.
Who is stealing virtual CPU time?
Hi! In this article, I want to explain, in layman’s terms, how steal appears in VMs and tell you about some of the less-than-obvious artifacts that we found during research on the topic that I was involved in as CTO of the Mail.ru Cloud Solutions platform. The platform runs KVM.
From High Ceph Latency to Kernel Patch with eBPF/BCC
There are a lot of tools for debugging kernel and userspace programs in Linux. Most of them have performance impact and cannot easily be run in production environments. A few years ago, eBPF was developed, which provides the ability to trace the kernel and userspace with low overhead, without needing to recompile programs or load kernel modules.
There are now plenty of tools that use eBPF and in this article, we’ll explain how to write your own profiling tool using the PythonBCC library. This article is based on a real issue from the production environment. We’ll walk you through solving the problem and show how existing bcc tools could be used in some cases.
Dozen tricks with Linux shell which could save your time
- First of all, you can read this article in russian here.
One evening, I was reading Mastering regular expressions by Jeffrey Friedl , I realized that even if you have all the documentation and a lot of experience, there could be a lot of tricks developed by different people and imprisoned for themselves. All people are different. And techniques that are obvious for certain people may not be obvious to others and look like some kind of weird magic to third person. By the way, I already described several such moments here (in russian) .
For the administrator or the user the command line is not only a tool that can do everything, but also a highly customized tool that could be develops forever. Recently there was a translated article about some useful tricks in CLI. But I feel that the translator do not have enough experience with CLI and didn't follow the tricks described, so many important things could be missed or misunderstood.
Under the cut — a dozen tricks in Linux shell from my personal experience.
System call interception in Linux-kernel module
Translation
The module was created as a part of my master thesis in the 2010 year. The master thesis theme is Keylogging in Linux kernel. The main idea was to find out a way to intercept system calls for x64 arch Linux kernel, especially for kernel 2.6.34.7-61.fc13.x86_64.
Test me if you can. Do YML developers Dream of testing ansible?
It is text version of the presentation 2018-04-25 at Saint-Petersburg Linux User Group. Configuration example locates at https://github.com/ultral/ansible-role-testing
I suppose that that you make configuration management, not bash. It means that you have to test it some how. Have you ever tested ansible roles? How do you do it?
How to test your own OS distribution
Let's imagine that you are developing software and hardware appliance. The appliance consists of custom OS distributive, upscale servers, a lot of business logic, as a result, it has to use real hardware. If you release broken appliance, your users will not be happy. How to do stable releases?
I'd like to share my story how we dealt with it.