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Linux Command & Tools

[Linux Commands] System Tools – Simple Disk R/W Performance Tests

Basic Concept Disk Cache Hierarchy Simple Disk R/W Performance Tests This section, I’ll use “hdparm” to do Disk read performance tests and “dd” to test Disk write performance. Both tools are single-threaded and use sequential-read/write to do test, that is hard to fulfill real-life. Anyway we also can use them to …

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Linux Command & Tools

[Linux Commands] System Tools –  Advanced Disk R/W Performance Tests

Basic Concept Disk Cache Hierarchy Simple Disk R/W Performance Tests Advanced Disk R/W Performance Tests by FIO FIO (flexible IO tester) is developed by “Jens Axboe” and he is the maintainer of the Linux kernel’s block layer. FIO is a powerful I/O performance benchmarking tool, it can be used to measure random IOPS …

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Concept

[Linux][System Concept] – Disk Cache Hierarchy

Disk Cache Hierarchy Page Cache (Operating System Cache) Linux kernels up to version 2.2 had both a Page Cache & a Buffer Cache. As of the 2.4 kernel, these two caches have been combined. Today, there is only one cache, the Page Cache. You may use free command to see the …

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Linux Command & Tools

[Linux Commands] System Tools – How to know the disk type ? HDD or SSD

The simple way to identify the Disk type is to check the info from sysfs. We can check the value of  /sys/block/{disk}/queue/rotational . ( why this file ? ) 0: HDD 1: SSD We also can use lsblk command to get this rotational info from sysfs. $ lsblk -o "NAME,MAJ:MIN,RM,SIZE,TYPE,MOUNTPOINT,ROTA" NAME MAJ:MIN …

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Linux Command & Tools

[Linux Commands] Tune “Reversed Block Count” of partition on ext2/ext3/ext4 filesystem

tune2fs command is used to adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems. More common use cases: View filesystem parameters, ex: Block Size Reserved block count convert ext2 filesystem to ext3 for adding Journaling feature with -j parameter. convert ext3 filesystem to ext4 with -O extents,uninit_bg,dir_index parameters. This site describe the detail about …

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Server stuff

How to verify which SSL/TLS Protocols are supported on the FTP Server

Today, I disabled SSLv2, SSLv3, TLSv1.0 and TLSv1.1 SSL/TLS protocols and remain TLSv1.2 only on my ProFTPd FTP Server. The configurations were configured but I still not sure if my settings are workable? So, I surveyed two ways to do that. 1. Use Python ftplib ( Preferable ) I prefer …

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Frontend - HTML/CSS/JS

[WordPress][Plugin] Code Embed & Advanced Custom Fields

Requirement Sometimes I learned some new syntaxes of Front-end technologies, ex: HTML, CSS and JS. I’d like to well present it on my post, like: Show the Source Code and Syntax. Display Code Result ( HTML + CSS + JS ). As I know, the simple way to do that is …

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Linux Command & Tools

[Linux commands] Network and Transport Layer diagnosis tools

Nmap ref: https://nmap.org/book/man-host-discovery.html  https://nmap.org/book/man-port-scanning-techniques.html nmap is a powerful command. It can be used to do port check, ping scan, ping check, traceroute and …etc. Common Parameters -n: no resolve hostname -sL: list only no real scan, it can be used to list the ip range of subnet -sP: ping scan. …

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Linux Command & Tools

[Linux commands] diff and patch usage and example

Note diff commands is able to generate patch file for both of File and Directory. Then, we would use patch command to patch File or Directory by the patch file. How to patch Scenario – File diff command usage diff -Naur {old} {new} > patch file patch command usage patch …

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Software Installation

[Linux] development tools environment

For me, I prefer to install all tools on /opt/tools directory. JDK Official site: http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html Download: jdk-*-linux-x64.tar.gz $  sudo tar -C /opt/tools/ -xvf jdk-8u131-linux-x64.tar.gz # create a link for easily use it $ sudo ln -s /opt/tools/jdk1.8.0_131 /opt/tools/jdk   Add below lines to .bashrc JAVA_HOME="/opt/tools/jdk" PATH=${JAVA_HOME}/bin:$PATH Maven Official site: https://maven.apache.org/download.cgi Download: apache-maven-*-bin.tar.gz …

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