Tag Archives: Linux - Page 14

How to check memory usage in Linux

Posted by on April 22, 2015 No comments

In the Linux operating system it is important to have enough free physical memory (RAM) available for your processes which need to run. If this memory runs out, swap space will start to be used next, which will result in slower performance as I/O operations will need to be written to disk instead. If both main memory and swap become full your Linux system can completely freeze up.

By checking and monitoring the amount of memory in use and confirming there is enough free memory to service requests we can ensure that processes continue to run optimally.

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Compiling NRPE and nagios-plugins for Solaris 11.2

Posted by on April 1, 2015 5 comments

I have some Solaris 11.2 storage servers which run a number of ZFS pools, I wanted to monitor these through NRPE via Nagios. To do this I needed to compile NRPE and nagios-plugins from source, this article covers how this was done.

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How to test network connectivity with telnet

Posted by on February 18, 2015 7 comments

This post is a follow on from my post last week regarding how to install the telnet client. The telnet client is simple yet extremely powerful in helping us gain a quick idea of where a problem may lie with TCP connectivity, it’s one of my first go to tools to use when testing a network connection to a server.

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Monitoring multiple back end Nagios/Icinga servers with Thruk

Posted by on February 4, 2015 4 comments

Thruk acts as a central web interface allowing you to monitor multiple backends such as Naemon, Nagios, Icinga and Shinken via the Livestatus API. I had some difficulty getting it connecting to my back end servers so here are the steps I took to get it done. By the end of this guide you should be able to add your back end monitoring servers into Thruk, we’ll cover adding an Icinga server in this instance however the steps will be very similar for a Nagios server, given Icinga is a Nagios port.

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Linux Server Maintenance Checklist

Posted by on January 7, 2015 1 comment

Server maintenance needs to be performed regularly in order to ensure that your server will continue to run with minimal problems, while a lot of maintenance tasks are automated within the Linux operating system now there are still things that need to be checked and monitored regularly to ensure that Linux is running optimally. Below are steps that should be taken in order to maintain your servers.

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Virtual machine not powering on in Citrix XenServer 6.2

Posted by on December 24, 2014 No comments

Today I connected to a CentOS 6 server via SSH and quickly noticed that the file system was in read only mode, after checking a few other Linux servers on the same XenServer host it quickly became apparent that there had been a network issue between the storage and compute layers which caused the Linux file systems to go read only in order to protect themselves.

After not being able to do anything useful within the operating system such as remounting the file system as read/write, I decided that it was time to reboot and force a file system check to pick up and fix any problems, however once the server had shut down it did not power back on as part of the restart task, it also did not power back on when attempting to start it up. This only happened to one VM, all of the others powered back on fine and worked as expected.

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Red Hat Certified System Administrator (RHCSA) 7 Study Guide – EX200

Posted by on May 17, 2014 43 comments

Today I got the results for the RHCSA EX200 exam which I took yesterday and passed with full marks, I received a score of 300/300 with the passing score being 210. This is just a quick review about the materials I used and how I studied to pass the exam, I hope that this guide will help you study! I will not be discussing any of the contents that were within the exam, if you’re interested in what is covered have a look at the exam objective page here.

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My top 3 Linux commands for logging problems

Posted by on December 20, 2012 2 comments

Here I will share a few useful Linux commands I have been using to troubleshoot various server problems. Logging is extremely useful especially when an issue happens at random times or you are not able to yet reproduce the problem. Going back over logs to when a problem was identified will provide you with information and insight into what caused the problem and the general state of the server during that time period, this is why I am covering how to perform logging with these useful commands. There are plenty of other useful commands that are useful for more specific troubleshooting, however I have found these ones the best overall for identifying issues.

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How to Increase the size of a Linux LVM by adding a new disk

Posted by on December 14, 2012 171 comments

This post will cover how to increase the disk space for a VMware virtual machine running Linux that is using logical volume manager (LVM). Firstly we will add a new disk to the virtual machine and then extend the original LVM over this additional space. Basically we will have two physical disks but just one volume group and one logical group that is using the space on both disks together. With this method there is no down time for the virtual machine.

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Use GParted to increase disk size of a Linux native partition

Posted by on December 13, 2012 118 comments

In this post we will cover how to increase disk space for a VMware virtual machine that is using a Linux native partition rather than logical volume manager (LVM). Firstly we will increase the size of the virtual disk on the virtual machine at the hardware level and then once this is complete we will boot into a GParted live CD and perform the changes required to make use of the additional disk space so that the operating system is able to use it.

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