Sparse files are common in Linux/Unix and are also supported by Windows (e.g. NTFS) and macOSes (e.g. HFS+). Sparse files uses storage efficiently when the files have a lot of holes (contiguous ranges of bytes having the value of zero) by storing only metadata for the holes instead of using real disk blocks. They are […]
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357 posts in total.
How to Add a File Based Swap for Linux
We may want to add some swap space for a Linux box while only find that all disk space is partitioned and mounted. Some partition has large available free space. For such cases, we may not want to change the partition allocation. The solution may be to add a file based swap for Linux as […]
Where Does Evolution Save Its Data and Configuration Files on Linux?
Evolution is a great personal information management tool that provides Email, address book and calendar tools. Evolution provides many enterprise friendly feature such as native support to Microsoft Exchange connectivity for Emails, address books and calendars. Evolution uses various ways including plain files and dconf configuration systems. This post will give an introduction to the […]
How to Export an NFSv4 Server to External Networks
We ever discussed fixing ports used by NFSv3 so that it can be easily exported to external networks. For NFSv4.1 or higher, things are much easier. The ports for mountd, statd, and lockd are not required in a pure NFSv4 environment. We have less ports to control or allow for connections. Only port 111 and […]
How to Add Custom Content on a Receipt
This blog will explain about how to add a custom content in a Receipt which will be generated from MPOS in Microsoft Dynamics. Microsoft provides us with certain fields which can be put into the receipt. There are certain fields which a client will ask to show in the receipt. If the desired field is […]
A List of Common Software on Windows
Quick links to some useful software on Windows including Web browsers, Video/audio player and ssh/scpsftp/vnc tools for connecting to Linux. ssh/scp/sftp/vnc for connecting to Linux ∞ For Linux users, it is sometimes unavoidably to use Windows. With Windows, the Linux users will need to connect to Linux for some tasks. Some general software are needed. […]
How to Implement Hibernate Envers in an Application
Technology Hibernate Envers is the frameworks for auditing entities. As the name suggests Hibernate Envers is developed on top of Hibernate, it will on Hibernate and Hibernate implemented JPA. Hibernate Envers provides easy auditing, versioning solution for entity classes. Advantages of Hibernate Envers: Auditing of all mappings defined by JPA specification. Auditing Hibernate specific mappings […]
Deploying ASP.NET Core 2.0 MVC application to Azure Web apps using Visual Studio 2017
Introduction In this tutorial, we will be learning as how to deploy .NET Core 2.0 MVC web application on Microsoft Public Cloud i.e. Microsoft Azure, using Microsoft Visual Studio 2017 v15.3 For novice Cloud developers, aspiring .NET / Cloud architects, and all other IT professionals associated with the .NET Core framework & Cloud computing, especially […]
A Beginners’ Guide to x86-64 Instruction Encoding
The encoding of x86 and x86-64 instructions is well documented in Intel or AMD’s manuals. However, they are not quite easy for beginners to start with to learn encoding of the x86-64 instructions. In this post, I will give a list of useful manuals for understanding and studying the x86-64 instruction encoding, a brief introduction […]
How to force a metadata checkpointing in HDFS
The metadata checkpointing in HDFS is done by the Secondary NameNode to merge the fsimage and the edits log files periodically and keep edits log size within a limit. For various reasons, the checkpointing by the Secondary NameNode may fail. For one example, HDFS SecondaraNameNode log shows errors in its log as follows. 2017-08-06 10:54:14,488 […]
How To Debug Linux Kernel With Less Efforts
Introduction In general, if we want to debug Linux Kernel, there are lots of tools such as Linux Perf, Kprobe, BCC, Ktap, etc, and we can also write kernel modules, proc subsystems or system calls for some specific debugging aims. However, if we have to instrument kernel to achieve our goals, usually we would not […]
QEMU/KVM Network Mechanisms
Introduction As we know, network subsystems are important in computer systems since they are I/O systems and need to be optimized with many algorithms and skills. This article will introduce how QEMU/KVM [2] network part works. In order to put everything simple and easy to understand, we will begin with several examples and then understand […]
I/O Microscopy: Tasks’ Disk I/O Information with High Accuracy
Abstract Most popular task monitor systems (such as top, iotop, proc, etc) can only get tasks’ disk I/O information like tasks’ I/O utilization percentage every seconds due to kernel timer/tick frequency and high time cost of system interfaces. This article presents I/O Microscopy, a new way to get tasks’ disk I/O information with high accuracy. […]
7 Common On Page SEO Mistakes You Are Making and You Should Not
With Google algorithm becoming more intelligent with each passing day, the margin for errors has significantly reduced over the past decade. Back in the day, you might get away with keyword stuffing but today, the same offense will strike off your website from Google search engine results. No one wants that, right. To save you […]
How Easy Is It to Perform SEO?
The word “viral” has received a lot of attention over the last few years and is applied to different types of content to describe how quickly it has spread and gained popularity. Many times, you’ll hear people speak about their idea and how fast it will spread while assuming that it will “go viral”, but […]
Call Forwarding for iPhone: How to Set up or Disable Call Forwarding in iOS
Call forwarding is useful if you are expected to be unavailable for receiving calls or lose cell phone coverage for some time. Call forwarding is not something that is "new" to modern phones. It is a feature which is invented in 1960s (the patent expired in 1980) of some telephone switching systems. But with iPhone/iOS, […]
Reference: Special HTML Characters
HTML supports many characters/symbols such as mathematical symbols, and currency symbols. They are not present on a normal keyboard. And some of these characters may have special meanings for formatting text. To add such characters / symbols to an HTML text, you can use an HTML entity name or an entity number in decimal or […]
Basic Knowledge of HTML and Canvas
From a small business owner, a blogger, a student or individual with a personal project, the need to create websites has never been more prominent. Having a basic understanding of HTML and canvas knowledge can be helpful, and it is simple to master. The thought of learning to code and programming may seem a long […]
How to Install Paravirtualized CentOS 7 DomU on Xen
This post introduces how to install a paravirtualized CentOS 7 DomU on Xen. The very common way of installing DomU does not work for CentOS 7. A little trick to set the repository and the network used by the VM should be used by adding a setting strings to the “extra=” field for this VM. […]
USB Standards and Supports in Linux
The USB standards have evolved to 3.1 and the supported throughput have been increased too. On Linux, the support to USB standards are following the standards development. In this post, we will survey the standards that common hardware support and the support in Linux. USB standards ∞ USB 2.0: https://en.wikipedia.org/wiki/USB#USB_2.0 Speed:
