Let's Automate System Health Check In Linux

Most of the modern day applications uses virtual systems which are cloud based hosted by some popular cloud service providers such as Amazon, Google, Azure, Verizon etc,. Since these systems are provisioned and maintained by the cloud service providers, the task of a Linux Administrator has gone reduced. Gone are the days when a Linux Admin spends hours of time in analyzing crash dump to understand the symptoms of reboot/crash and finding out ways to tune the system. So, in this virtual world, application vendors doesn't really bothered or interested if a virtual machine crashes, because they get to host the services on another virtual system with absolutely zero or minimal downtime. All such tasks of maintaining virtual systems are done by cloud providers. Hence, from application perspective there are no worries as such. However, there are times when it is required to track/monitor a Linux system health which is hosting some applications.

RHEL 8 Beta: Bits & Pieces

Yes, Red Hat has recently released the Beta version of Red Hat Enterprise Linux (RHEL) 8.  This is still in a rigorous testing and development phase, so there could be some changes compared with ‘Stable’ release later. As everyone I was also keen on installing the ‘beta’ version and checking how it works, what are the differences, what’s new, what is not available etc., hence, I thought of writing up this post to give a glimpse of RHEL 8 beta.

How-To Recover Accidentally Deleted Disk Partition In Linux?

There are many a times that we’ve come across this situation where an “hard drive partition table has been erased accidentally” or “partition data is missing or corrupted” and hence, unable to mount respective block devices. Yes, “how to recover or repair corrupted or deleted partition table of a hard drive” or “how can I recreate hard drive partition table without losing data” are some of the keywords that we hit on Internet to find out a solution. There are a few third party tools (many from open-source) available which could get this job done, however, I wanted to show how this could be done using native tools/commands in Linux operating system. There are at times that we could not use those third party tools, hence, we’ve to go with native way of restoring partition table data. So, let’s see how could we get this achieved. NOTE: If a hard drive is extremely damaged (physically) or if it is re-formatted (making a file system) or if meta-data itself is gone corrupted or severely damaged then there are very less chances of recovering data, in such cases users may have to rely on some sophisticated third party tools which may recover some or part of data. The situation that I’m going to cover here is wherein a hard drive partition table is erased, however, no re-formatting has been done yet.

How-To Recover Accidentally Deleted Disk Partition -Part2

Method 2

The earlier method was a bit lengthy and needs proper planning and implementation. Now, let’s discuss about using “parted” tool to recover corrupted or deleted partition table details. This method is rather easy and straight farword which doesn’t need so many steps to be performed as we did earlier.

The “parted” tool is a powerful disk utility which can do many functions such as recovery of partition data, resize etc., and also the default utility being used if disk size is greater than 2.2TB. Another powerful feature of “parted” is that it is GPT aware.

How To Resolve Kernel Panic Error After Installing A New Kernel?

“Kernel panic after installing a new kernel” is a situation that most of the people (admins/staff) who manages a Linux box would have come across or heard off. So, “how to resolve kernel panic error after installing a new kernel” or "kernel panic after system updates" would be the keywords that we most of us hit on internet search engine… Google to check for solution. This happened with me as well, and I had to look out for a proper solution and did a lot of research about this. Hence, I wanted to document about kernel package, prerequisites to be checked before installing a new kernel, various methods used to cross-check if new kernel is successfully installed etc., which could help someone looking out for an answer/solution regarding this. There may be a situation where a system fails to boot into new kernel and shows some other errors and it may not be a panic message.

How To Troubleshoot When System Drops Into GRUB Rescue Shell?

One of my Linux servers (RHEL 7.5) dropped into grub rescue shell and had failed to load the operating system. So, I was troubleshooting it and discovered a few steps which could help anyone who is in need, hence, I decided to write this post in my blog site. This post talks about step by step procedure to recover such a Linux system and boot normally.  This is tested and re-produced on a virtual system running on VMWare Workstation.

I’m going to document each step with screenshots in this post which would help anyone who wish to recover such failed system.