Saturday, January 18, 2020

How-To Safely Remove A Storage Device From A Linux System

There are situations where we would be required to remove a storage device or LUN from a system and attach it to another system for some other important purpose. So, how could this be achieved? Yes, we could remove a storage device attached to a system safely provided the system has enough bandwidth to accommodate data on another available volume. In this blog page, I’ve tried to document all the steps with screen-shots to demonstrate the same procedure. I hope this helps someone and if so, please leave a comment or hit Like button. Thank you!

Monday, November 11, 2019

Learn Linux The SUSE Way

Yes, you heard it right. SUSE has been doing a good thing in enabling enterprise sector to be technically capable enough to cater to the needs. That’s right. SUSE has been conducting free technical training plus certifications to partner companies. They also would ready to go to the respective locations of the partner to deliver training's*.

This is significantly a different & great approach when compared with its competitors. Definitely, the company SUSE has been investing a lot on this approach. Anyone who is interested and wish to skill up would certainly could register for required course and start learning. There is also an option to learn online as well. 

Friday, August 23, 2019

Main Differences Between RHEL & SLES

Red Hat Enterprise Linux (RHEL)SUSE Linux Enterprise Server (SLES)
Owned ByRed Hat
Red Hat, Inc is an American MNC with head office in Raleigh, North Carolina (USA). It was founded in March 26th 1993. Now, it has been acquired by IBM.
It is a German based software MNC, founded in 1992 and headquarter located at Nuremberg, Germany.

Tuesday, June 11, 2019

Steps to fix or resolve Error 15 or Error 17 or No files under /boot.

We get to see “Error 15” or “Error 17” when the ‘/boot’ file system is corrupted, so system fails to boot up. This is mainly because of primary boot loader files missing or not found. It could also be possible that the ‘/boot’ file system has been overwritten or formatted by mistake. 

Friday, May 17, 2019

Common Debugging Methods In Linux

The top 6 common debugging methods in Linux.

( 1 ) Increase logging verbosity
As usual, in Linux systems we could look out for errors/warnings/info related messages in "/var/log/messages" file. By default only ‘info’ ( information) and above messages gets logged in to this file, so to increase this logging verbosity one could edit the configuration line of "/var/log/messages" in "/etc/rsyslog.conf" file.

Change this line from :
*.info;mail.none;authpriv.none;cron.none                /var/log/messages

*.debug;mail.none;authpriv.none;cron.none                /var/log/messages

After making this change, save and exit the file. Restart the “rsyslogd” service ( 'systemctl restart rsyslog.service' or 'service rsyslog restart' in case of RHEL6.x and older) to make the changes come into effect. NOTE: Keep in mind that this would generate a lot of logs and "/var" may get filled up fast, so after the diagnosis make sure to revert the changes.

Sunday, March 3, 2019

What Is Firewalld & How To Configure Rules?

Image result for firewallIn this post we’d talk about ‘firewalld’ and it is benefits and how to get it configured in RHEL7 and above systems.

A Note on netfilter

In Linux ‘netfilter’ is being used which is a powerful network filtering sub-system. This allows kernel modules to inspect each packet traversing the system, and it could be dropped or rejected or allowed in a programmatic way and this applies to all incoming, outgoing and forwarded packets. So, in earlier RHEL6.x version there is ‘iptables’ being used which is a well-known netfilter program. However, in RHEL7.x version and above we've ‘firewalld’ in-place of ‘iptables’.