≡ Menu

Linux

How to enable colors in shell and vi in Mac?

When working with shells, if your Mac does not show various colors automatically, you can enable them by two easy steps.

First add a line as shown below to your .bash_profile. This file should be under your home directory.

export CLICOLOR=1

Second, add the following line in your .vimrc file. This file should be under your home directory. If it is not there, create one.

Read More

What is Virtualization?

Virtualization is a technique using which you can run multiple Operating Systems (aka Guest) in a physical server (host) by abstracting (or virtualizing) CPU, Memory, Disk and Network resources. The core component of any virtualization solution is Hypervisor – the software that performs the abstraction of bare metal resources.

Here are the primary benefits of using Virtualization:

  1. Save cost on hardware
  2. Centrally manage the infrastructure
  3. Add effective fault tolerance and high availability
  4. Dynamically update the infrastructure

The diagram below shows virtualization at a high level.

Read More

5 reasons why you can’t afford NOT to Virtualize

The verdict is in. Virtualization is the future. If you are still running your applications on bare metal, you are missing out on tons of benefits, or even hurting your business. Virtualization is a software tech that lets you run multiple operating systems and applications on a physical server by abstracting the hardware underneath. Among several Virtualization software makers, the following are considered leaders:

VMWare (ESXi)

Citrix (XenServer)

Microsoft (Hyper-V)

Let’s dive in to 5 reasons why you can’t afford NOT to virtualize (not necessarily in any order)

Read More

How to use AppDynamics to monitor Server health?

Yes, AppDynamics is awesome for Application monitoring – Java Heap, deep transaction tracing, tons of out-of-the-box framework monitoring (JDBC,WebService etc) and the list goes on. But do you know Appdynamics can be used to effectively monitor Servers too, whether it is virtual or physical? When I say server, I mean the host operating system such as RedHat Enterprise Linux, Windows 2012, Solaris etc. Let me show you how you can do this.

Enter AppDynamics Machine Agent

While Java can be monitored using a Java Agent, a Server can be monitored using a special type of agent called Machine Agent. You will have to have license to run these agents (When you purchase Application agents, typically AppDyanmics throws the same number of Machine Agents, and so you should be good in terms of additional cost). If you are not sure about your present licensing situation, click on ‘licensing’ in your Controller UI as shown below.

Unlike Application agents which run inside the JVM/CLR, Machine agent is a standalone Java program that runs on the host operating system. It collects hardware metrics and sends them to Controller (once a minute). A user can view these metrics via Controller UI. Pretty simple, hah?

Read More

How to install Apache Web Server using Yum?

Software installation has never been more fulfilling since YUM came along.

YUM is the most popular rpm based interactive package manager. It is super powerful and reliable.

In this quick article, I show how to install apache web server, the world’s most popular web server in your Linux Server.

You need to have root access to do this. You also need to have internet access on the server you are installing apache.

Simply run the command

sudo yum install httpd

That’s it. Yum does the rest.

Once done, which takes about 10 seconds, start the httpd server

Sudo service httpd start

Once the service starts, simply use a browser to access the server (use the default server name or the ip address).

Or you can choose the geeky way to use curl to test out. I created a basic html file. Here is how to access it

Curl http://localhost/index.html

You can check access.log to see how you did. Access_log is present under /var/log/httpd/

The configuration file for apache (httpd.conf) will be under /etc/httpd. (This depends on your platform).

That’s it. Your own enterprise grade Web Server, up and running in about 10 seconds.

Way to go YUM !!

Buckle up! You can get your own AWS server in cloud. You can run a verity of OS on it, connect to any popular Database you want to and even get your hands on some of the coolest products from AWS. I don’t know about you but I’m psyched about all this.

apm

Yes, Amazon Web Services Free Tier allows you to have your own Server in EC2 for 12 months. If you are new to AWS, this is a great way to get your feet wet, or may be drenched.

This article shows exactly how you sign up and crank up your own server in cloud. It takes about 15 to 20 minutes to get your hands on a brand new Amazon Linux instance (or Windows or Suse or RHEL…..)

Without further due, here are the actual steps to follow.

Read More

Introduction to APM: Benefits of APM

So, what can an APM tool buy you? Setting aside the hypothetical ‘Peace of mind’ marketing pitch, let me show you how exactly an APM tool can help you support your Application effectively

1. Historic Monitoring of Key Metrics

APM tool can record the monitoring metrics which are invaluable in troubleshooting. For example, take a look at the ‘response time’ graph of a particular application. You can readily see that the application suffers during business hours.

Historic

Read More

Introduction to APM (Application Performance Management)

Back in the 90s when I was working as a Solaris/HP-UX Administrator, all I needed was two or three commands to figure out what was wrong with a particular Server or Application. I will just glance at ‘vmstat’, ‘iostat’ and ‘top’ for a minute or two and the problem will reveal itself clearly. While those command still prove valuable at a certain level, in order to answer ‘Why is the application slow’ you need much more than just few OS commands.

Read More

The most important JVM memory tuning parameter- and how to ace it.

One of the deadliest errors you can encounter in your Java application is ‘OutOfMemory’ error. The impact this error can have in your application and your business can be enormous. I have seen organizations spend countless hours struggling to fix this error while continuing to have degraded end-user experience (a sure-fire way to lose credibility). One company was actually restarting their application every three hours just to avoid an ugly hang due to OOM. How sad?

In this article, I would like to point out the most important tuning parameter in your Java application. If you get this wrong, no matter how much tuning you put in, you will end up with an OOM sooner or later. Note that there are tons of tuning parameters available to tune the memory. Most of these may not have any effect at all, and some have game-changing effect. The parameter I’m about to reveal is of later kind and the mother of all parameters. This should be the first parameter you should be analyzing to zero-in.

Without further due, here it is.

Read More

Video – Important things you need to know about shellshock