Home
FlamingBytes
Cancel

Using node selector to assign virtual mahcines to a node

In some circumstances, we want to control which node the virtual machine or pod deploys to. The node selector can be used to assign virtual machine or pod to a node. Add label to a node The label...

Understanding thin provisioning volume and snapshot

Thin provisioning volume Logical volume can be thinly provisioned. It allows storage administrator to overcommit the physical storage. In other words, it’s possible to create a logical volume whic...

Using virtctl to access virtual machine in Kubernetes

Install the virtctl client tool Basic VirtualMachineInstance operations can be performed with the stock kubectl utility. However, the virtctl binary utility is required to use advanced features su...

How to configure SAR data collection on RHEL8

On RHEL8, it uses systemd instead of cron jobs to manage SAR data collection service. Run the following command to check if the SAR data collection is started. [root@h04-11 ~]# cat /etc/redhat-re...

libaio init failed due to resource temporarily unavailable

Issue Description $ sudo fio --blocksize=64k --directory=/mnt/bench1 --filename=testfile --ioengine=libaio --readwrite=randread --size=10G --name=test --numjobs=512 --group_reporting --direct=1 --...

How to uninstall ceph storage cluster

Check the pools, images and OSDs [ceph: root@host1 /]$ ceph osd tree ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF -1 83.83411 root default -3 27.94470 ...

How to run fio on multiple files

fio directory and filename option directory=str Prefix filenames with this directory. Used to place files in a different location than ./. You can specify a number of directories by s...

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 raw device or filesystem

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...

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 -...