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fio benchmark on multiple devices

In this post, we study how to run fio benchmark on multiple devices. We also try to understand how the iodepth reflects on each device. We start with single device and the following global paramet...

Backup and restore MySQL database

Backup a database mysqldump is a command-line utility which can be used to generate backups of MySQL database. $ mysqldump -u root --password=<db_password> mydb > mydb_dump_`date +"%Y%m%...

Create Image Gallery in Jekyll without Plugin

An image gallery can be easily built by using LightBox and Image Gallery scripts in Jekyll. LightBox Lightbox is a solution that loads your image links, your Youtube links and your Vi...

Using sysbench for OLTP workload performance benchmark

Intro to Sysbench sysbench is a scriptable multi-threaded benchmark tool based on LuaJIT. It is most frequently used for database benchmarks, but can also be used to create arbitrarily complex wor...

An easy guide to install kubernetes cluster with kubeadm

Kubernetes can be installed with the following deployments tools. Bootstrapping clusters with kubeadm Installing Kubernetes with kops Installing Kubernetes with Kubespray In this article,...

Vdbench performance test on filesystem

File system testing - Method 1 Vdbench filesystem testing terminologies: Anchor - A directory or a filesystme mount point. A file system structure will be created by specifying the structure i...

Vdbench performance test on raw device

Terminology Master and Slave: Vdbench runs as two or more Java Virtual Machines (JVMs). The JVM that you start is the master. The master takes care of the parsing of all the parameters, it...

Deploy ceph cluster on Ubuntu 18.04 and CentOS 7.8

In this article, we learn to deploy ceph cluster on ubuntu 18.04. Three nodes are used for this study. We target to deploy the most recent ceph release which is called Pacific. With this release, ...

Capture and analyze network packets with tcpdump

Capture packets with tcpdump In this example, we only capture 1000 packets(-c1000) and use IP addresses and ports(-nn) for easier analysis. The raw packets are written to file “tcpdump.1000” for f...

Useful tools to analyze network latency

ping Ping is one of the most basic commands in network management, verifying network connectivity through the roundtrip times taken by the ICMP protocol packets sent to a target host. ping - send...

A modern asynchronous I/O interface for Linux

The Linux kernel has had asynchronous I/O since version 2.5, but it was seen as difficult to use and inefficient. io_uring (previously known as aioring) is a Linux kernel system call interface for...

btrfs - A modern copy on write(CoW) filesystem for Linux

Introduction btrfs is a modern copy on write (CoW) filesystem for Linux aimed at implementing advanced features while also focusing on fault tolerance, repair and easy administration. Its main fea...

Setting up LVM volumes on a mdraid array

Setting up mdraid array $ mdadm --create /dev/md0 --name=mdvol --level=raid0 --raid-devices=2 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme3n1 /dev/nvme4n1 mdadm: Defaulting to version 1.2 metadata mdadm: a...

Linux Software RAID

What is RAID? RAID stands for either Redundant Array of Independent Disks, or Redundant Array of Inexpensive Disks. The intention of RAID is to spread your data across several disks, such that a s...

RAID - Redundant Array of Inexpensive Disks

RAID stands for Redundant Array of Inexpensive (Independent) Disks. On most situations you will be using one of the following four levels of RAIDs. RAID 0 RAID 1 RAID 5(6) RAID 10 (also k...

Upgrade kernel version in centos 7

Before upgrade $ cat /etc/centos-release CentOS Linux release 7.4.1708 (Core) $ uname -r 3.10.0-693.el7.x86_64 $ cat /boot/grub2/grubenv saved_entry=CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core)...

Migrate docker data to different directory

This post guides us how to migrate the docker data from the existing directory to a target directory in the case that the old directory runs out of space. Stop the docker daemon $ cat /etc/centos...

Using gstack for docker container process

In a Docker container environment, we won’t get a valid stack trace directly on the container host as below. $ ps -ef |grep smbd root 171118 167977 0 Apr22 ? 00:00:02 /usr/sbin/smbd -...

Network bonding

Introduction Network bonding enables the combination of two or more network interfaces into a single-bonded (logical) interface, which increases the bandwidth and provides redundancy. If a specifi...

Enable ssh passwordless login

Install sshpass package To install sshpass package on the source server from which to enable ssh passwordless login to remote servers: -bash-4.2# rpm -ivh sshpass-1.06-1.el7.x86_64.rpm Enable s...