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Using kubeconfig to configure access to remote Kubernetes cluster

Install kubectl binary The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster res...

Set up CockroachDB cluster with HAProxy load balancing

Each CockroachDB node is an equally suitable SQL gateway to your cluster, but to ensure client performance and reliability, it’s important to use load balancing. Performance: Load balancer...

Understanding Azure disk bursting

Currently, there are two managed disk types that can burst, premium SSDs, and standard SSDs. Other disk types cannot currently burst. There are two models of bursting for disks: An on-demand burst...

Setup CockroachDB in docker container

Create docker volume Create docker volume on each host: [root@host1 ~]# docker volume create --driver local --opt type=ext4 --opt device=/dev/nvme2n1 vol1 [root@host1 ~]# mkfs.ext4 /dev/nvme2n1 [...

Using netstat to check network package retransmission

$ while [ 1 ]; do netstat -s | grep 'segments retransmited' ; sleep 1; done 2500906 segments retransmited 2500912 segments retransmited 2501072 segments retransmited 2501102 segment...

CockroachDB TPC-C performance benchmarking

Provision VMs Create 4 VM instances, 3 for CockroachDB nodes and 1 for the TPC-C workload. On each VM, disable firewall and enable ntp service. $ systemctl stop firewalld $ systemctl disable fir...

CockroachDB performance benchmarking

CockroachDB key concepts Range - CockroachDB stores all user data (tables, indexes, etc.) and almost all system data in a giant sorted map of key-value pairs. This keyspace is divided into...

Deploy CockroachDB in kubernetes cluster

Deploy Kubernetes cluster $ kubectl get nodes NAME STATUS ROLES AGE VERSION node0 Ready <none> 115d v1.19.2 node1 Ready <none> 115d v1.19.2 node2 ...

Compile Linux kernel on CentOS

Build preparations To perform a successful kernel build, the following packages need to be installed: yum groupinstall “Development Tools” yum install ncurses-devel yum install qt3-devel (...

Deploy systemtap on multiple systems

Normally, SystemTap scripts can only be run on systems where SystemTap is deployed together with the following required kernel packages. kernel-devel-$(uname -r) kernel-debuginfo-$(uname -r) ...

Using systemtap to analyze latency of the kernel module function

In this post, we continue to explore how to use SystemTap to analyze the latency of the kernel module function. In the following example, we want to analyze the latency of the function “nfsd_vfs_wr...

Getting started with systemtap for Linux system profiling

Intro to SystemTap SystemTap is a tracing and probing tool that allows users to study and monitor the activities of the operating system (particularly, the kernel) in fine detail. It provides info...

Using ftrace to analyze latency of the kernel module function

In this example, we study the latency of the function “nfsd_vfs_write” from kernel module “nfsd”. ftrace configuration The following ftrace options are used in this example. There are 8 nfsd proc...

Dynamically tracing with user-defined tracepoint in perf

In this post, we are going to explore how to use perf for dynamic tracing with user-defined tracepoint. When we say dynamic tracing, the kernel event(function) to be traced is not predefined in per...

tuned - dynamic adaptive system tuning daemon

Tuned Tuned is a daemon that uses udev to monitor connected devices and statically and dynamically tunes system settings according to a selected profile. Tuned is distributed with a numb...

Install and uninstall debuginfo package on CentOS

Install debuginfo package On CentOS, we can install debuginfo package as below. Modify /etc/yum.repos.d/CentOS-Debuginfo.repo by setting “enabled=1” Run “yum install kernel-debuginfo” [roo...

Using sar to understand system activity

About sadc and sar sadc is known as system activity data collector. It samples system data a specified number of times (count) at a specified interval measured in seconds (interval). It writes in ...

Using nconnect to improve NFS performance

The nfs mount option “nconnect=n” exists in all Linux distributions with kernel 5.3 or higher. nconnect enables multiple TCP connections for a single NFS mount. From the nfs manual page: nconn...

How to setup NFS (Network File System) on RHEL/CentOS

We need to install NFS packages on the NFS Server as well as on NFS Client machine. We can install it via “yum” for RHEL/CentOS. On the NFS server side, run the following commands to setup NFS ser...

SysRq - Linux Magic System Request Key Hacks

What is the magic SysRq key? It is a ‘magical’ key combo you can hit which the kernel will respond to regardless of whatever else it is doing, unless it is completely locked up. How do I enable t...