Five Steps to Secure Your Linux System

Five Steps to Secure Your Linux System

http://bit.ly/11cAzbk

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Cassandra Multi Node Cluster Setup



Cassandra Multi Node Cluster Setup

In this article we will talk about cassandra multi node cluster setup in brief and very straightforward manner.

If you are new to Cassandra then you can follow this post to learn how to create a single Cassandra node. If you know how to setup single node than you can start from here. For a multi node cluster I will be using three virtual machines hosted on Xen Server. Setup all the three nodes as described here. Verify that all the three Cassandra nodes are up and running.

To configure multi node setup do the following :

Step 1. Locate Cassandra.yaml and search for ‘seed’. Change the IP address to the IP Address of any one node whom you want to designate as ‘seed’ (more on seed later).

Step 2. Change listen_address to local IP (should not be 127.0.0.1)

Step 3. Change rpc_address to local IP (should not be 127.0.0.1) Repeat the configuration changes for all the nodes and run this command to verify :



./nodetool status
Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
-- Address Load Owns (effective) Host ID Token Rack
UN 172.22.67.101 42.78 KB 25.4% 6fb0a0cb-b804-4f57-8178-d2c9f36bfac4 -5882736283116946676 rack1
DN 172.22.67.102 60.04 KB 31.8% 9e675cf5-f428-4770-8e73-38dc4338bf80 7869867229365366303 rack1
UN 172.22.67.103 62.13 KB 42.8% 8e87c60c-ef07-4ed6-83d0-0dc79f5094e4 2008276574632865675 rack1

(note : x’s are just used to hide real IP-Addresses),

If you can see something similar then you have successfully setup the cassandra multi node environment. In case you are having issues just comment and together we will try to resolve them.

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Measuring bandwidth in linux

Measuring bandwidth in linux

Wondering how to measure bandwidth usage on linux, its not that complex just install vnstat. On most linux systems it shows ‘fail to start’ due to unavailability of database. You need to create one, again even this is very simple.You will see this error on Ubuntu :No database found, nothing to do. Use –help for help.A new database can be created with the following command:
vnstat -u -i eth0Replace ‘eth0′ with the interface that should be monitored.The following interfaces are currently available:
lo eth0 wlan0

Simple isnt’t you know what to do, just use vnstat -u -i I used wlan0 to monitor bandwidth usage for wi-fi. As soon as vnstat starts to gather data, it will start showing up. Voilaaa…..Enjoy and measure bandwidth in linux.

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Installing Cassandra on Ubuntu 12.04

Installing Cassandra on Ubuntu :

This is an introductory article for installing cassandra on Ubuntu and basic usage. This will take you from installation and basic troubleshooting to inserting and fetching data. I assume that you already know what Cassandra actually is, if not you can read about Cassandra here:

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