Monitor Real time resource usage in CloudLinux :: lvetop

CloudLinux is one of the widely used Operating System now-a-days due to the high level stability and advanced server security it provides, which makes it the first preference to hosting providers, especially in shared hosting environment.

LVE (Lightweight Virtual Environment) is a kernel level technology developed by the CloudLinux team. It is lightweight and transparent. The goal of LVE is to make sure that no single website can bring down your web server.

The kernel makes sure that all LVEs get fair share of the server’s resources, and that no customer can use more than the limits set for that customer.
Continue reading…

Zend OpCache

The Zend OpCache provides faster PHP execution through opcode caching and optimization. It improves PHP performance by storing precompiled script bytecode in the shared memory.

Installing Zend OPCache on PHP 5.3 or 5.4

1. Login to SSH on your server

2. Type the following commands:

#cd /usr/local/src

#wget http://pecl.php.net/get/ZendOpcache

# to get the latest (master) build do the following instead:

Continue reading…

Icinga2 for centos7

Icinga is a fork of Nagios monitoring system. There are lots of changes and upgrades compared to Nagios, especially in version 2. The main visible difference is UI which is built on ext js. Other significant differences are in hosts and services definitions. Icinga2 designed to monitor large complex environments.

Pre-requisites

We need to make sure Install LAMP stack and epel repository on the CentOS7 server for other dependency application which will support icinga2 . Icinga2 will collect the service information based on the monitoring plugins, so we need to install nagios plugins. Also we should install IDO modules for MySQL which will use for Icinga2 Web interface and other web interfaces. Then setup MySQL database (create icinga DB and  import Icinga 2 IDO schema into database).  Web interfaces and other icinga addons are able to send commands to Icinga2 through the external command pipe, for that we need to setup external command pipe.

Setup Icinga Web 2 Interface

Continue reading…

The extra second in June 30, 2015 – The Leap Second !

The International Earth Rotation & Reference Systems Service (IERS) has mentioned that an extra second is to be added to Coordinated Universal Time (UTC) at 23:59:59 on 30 June 2015 and this is to make sure the alignment of astronomical and atomic time.

Coordinated Universal Time, UTC is one of the basic time conventions used by most of the world’s local time zones. This UTC time convention has been derived from a bunch of atomic clocks that are distributed across several countries globally.

The rotation of our earth is not so constant and it changes a bit over time and in-turn it decreases the mean rotation speed slowly. This is the exact cause behind leap seconds that gets added up to the UTC time scale, as they adjust the process of the UTC time itself to scale the real earth rotation.

This 1 second adjustment have hardly affected the normal human lives till now. But high performance timekeeping is most important for scientific and economic computing because even a second interruption may become stunningly important in these technologies. This scenario was last observed in 2012 when a second was added to the world time. Websites like Foursquare, Reddit, LinkedIn suffered glitches as the extra second got added because their system clocks were unable to figure out the sudden change.

In fact, on June 30, 2015 when the clock stuck 23:59:60, this will cause problems to many scientific and economic computing systems which are not programmed for this additional time. As conventional computing systems depend on precise time by using the Network Time Protocol (NTP) to be in match with the world’s atomic clocks, issues are expected, as many systems are not programmed for this extra leap second.

The International Earth Rotation and Reference System Service (IERS) in Paris, France observes the time between earth’s rotation and the atomic time. When the difference between the two approaches 0.9 seconds, they order a leap second to be added worldwide.

The workaround for this in our Linux machines is to reboot the server before the leap second period and then execute “date -s now” command in the server so as to update the leap second in the server.