Friday, February 2, 2018

A few advanced differences between RHEL7.x & RHEL6.x

Extracting initramfs image :--

Using "skipcpio" command in RHEL7.x, otherwise, we use "gunzip" in earlier RHEL versions. So, the command to extract initramfs image file in RHEL7.x is " /usr/lib/dracut/skipcpio /boot/initramfs-$(uname -r).img | gunzip -c | cpio -id ". In earlier versions, we could do this by using the command gunzip "gunzip -c /boot/initramfs-$(uname -r).img | cpio -i -d ".

Thursday, January 4, 2018

Introduction To Ansible ............. Simple, Easy & it is YAML

Now-e-days we get to hear a lot about automation specifically Infrastructure Automation. Technology has already shifted gears towards automation way of controlling IT Infrastructure. This is much needed for today's fast/rapid changing technology or infrastructure as demands from customer end does also took a sharp turn from way of investing/setting up infrastructure towards hosted infrastructure which we call it as "Cloud". A commonly used term which basically allows/facilitates converting physical infrastructure into a framework which is easy to scale-up & flexible that provides a virtual platform where everything is defined as service i.e majorly as IaaS (Infrastructure As A Service), PaaS (Platform As A Service) & SaaS (Software As A Service). There is a similar wing where activities of operation and development could be closely associated which we commonly call it as "DevOps".  Yes, I'm talking about one such tool that is being used to automate tasks in infrastructure which is "Ansible". A simple, easy to use, easy to automate tasks i.e to write playbooks and easy to is YAML (Ain't Markup Language). In this blog page, I wanted to talk about a few introductory points about Ansible and a little about installing and setting up.

Wednesday, December 6, 2017

Linux Performance issues - How/where to start with?

There are many a times that we find a server performing slow (specifically a Linux system ) compared to previous days or sluggish or in a worst case systems responds slow i.e running a simple command such as “ls” would take almost a minute to respond. So, at that juncture a system admin or person in charge of system would be in a dilemma on what is causing such slowness, is that because of processor (CPU overloaded), or memory (high memory usage) or network (slower network channels) or disk (poor performance of disk drives) or a bug with application or kernel. No amount of tuning would help if a hardware component is broken. Identifying bottlenecks at this point of time would need a proper analysis of system sub-components. Therefore, I came up with this page which documents simple steps/instructions/navigation which can be used to identify culprit for system slowness and later more advanced steps/commands could be used to dig further (only a few most followed commands and steps are documented here i.e native).

Thursday, October 26, 2017

Step By Step Procedure To Change Boot Device In RHEL6

If you’ve ever come across a situation where there is a need to change the boot device then this document explains a step by step procedure with screen images on how to get this done. There are situations wherein the initial boot device selected is of less capacity and later there is a need to change this to something bigger one. So there is no way to increase the size of this drive since the next block device which is usually “/dev/sda2” starts from the sector wherein the “/dev/sda1” ended (*considering installation done in default mode).  Hence, we’ve to plan to move all the boot files onto a new, bigger block device and make that as a bootable.

Friday, October 13, 2017

Main Differences Between MBR & GPT

A few points about GPT(GUID Partition Table) when compared with MBR(Master Boot Record) partitioning method for hard disk drives. GPT is a standard partition layout for storage devices used in a desktop or server, such as a hard disk drive or solid-state drive. GPT has many advantages when compared with traditional MBR scheme.  Ideally, GPT is being used on servers with bigger disks volumes and MBR still remains as a favorite for home based systems such as desktops, otherwise on older server systems with disks of lesser size . Normally parted utility would be used for larger disks which would create GPT partition scheme which otherwise performed by traditional disk utilities such as fdisk, cfdisk etc, (on Unix systems). These disk partition tools normally work for smaller disks and can only create MS-DOS partition tables, and got a few drawbacks which are overcome by parted tool.