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...

Solve LeetCode problems in Visual Studio Code

Install the leetcode extension in VS Code Login to LeetCode endpoint with cookie Login to leetcode from Google Chrome In Chrome, Inspect -> Network -> Fetch/XHR Click on any button...

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 ...

fio benchmark on multiple files

fio directory and filename options To run fio benchmark on multiple files or deives, we should understand the following fio options. directory=str Prefix filenames with this director...

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...