How do you handle Linux System Administration emergencies?

Navigating Linux emergencies is my art: 1. Instinctive Analysis: I decode the issue swiftly, unraveling the core and potential fallout. 2. Emergency Control: Like a skilled captain, I isolate the glitch, averting chaos. 3. Clear Signals: I light up the situation with precise updates, keeping everyone on board. 4. Smart Prioritization: Just as a conductor leads an orchestra, I fix critical elements first. 5. Solution Symphony: I orchestrate solutions, restoring harmony. 6. Crafted Records: I chronicle the journey—issue, fixes, and resolution—as a guide for the future. 7. Encore Review: After the storm, I review the performance, refining my playbook. 8. Knowledge Harvest: I gather wisdom from each saga, enriching my Linux odyssey.

Effective monitoring and logging play a pivotal role in troubleshooting. They enable meticulous analysis of issues in relation to timestamps, allowing for precise identification and a refined list of potential root causes.

"Start the bus". This is what they tell you when you're dealing with a medical emergency - call the ambulance. The sysadmin equivalent is to assess the scope of the impact and inform management. You do not need root cause at this point and looking for it now is a waste of time. What you want out of management is access to resources. Document absolutely everything. Who you talked to, what they did, and when it happened. Name names because that will help with root cause analysis in the next while. Be prepared to head up or cooperate with a 'tiger-team'. It is important to be open with other teams at this point and trust leadership to provide both resources and protection.

In addition to the tools and commands mentioned in the article, I would also recommend the following: #Use a checklist. A checklist can help you to ensure that you have not forgotten to consider any important factors. #Document your findings. Documenting your findings will help you to track the progress of the incident and to make sure that you do not miss anything important. Here are some additional points that could be added to the article to add value: # The importance of remaining calm and collected during the assessment process. # The importance of communicating with stakeholders throughout the assessment process. # The need to be prepared to escalate the incident if necessary.

Sufficient monitoring is key. Metrics and data on the systems you manage are as important as the system itself. Once you have adequate data in place you can spot and alert on any issues that may arise with speed. Piping your logs into something like Loki, ElasticSearch or another log aggregator allows you to quickly sort through, search and diagnose the cause of an issue which in turn will allow you to take action. Multiple tools can be used on the node itself to diagnose an issue but adequate logging can be invaluable for getting to the bottom of a problem.

Nothing provides data better than production, but do not blindly make changes there. Hypothesize, model, test, and deploy in preprod. You have a preprod, right? Make sure management is in the loop for every step of the way and call your shots clearly, and why you want to do them. They have higher-ups too. Once you have a working fix, plan and deploy in production.

I would also recommend the following: Use a risk assessment. A risk assessment can help you to identify the potential risks associated with each method or technique, and to choose the one that is the least risky. Get approval from stakeholders. Before applying the fix, it is important to get approval from the relevant stakeholders, such as the business owners, IT managers, and security team. This will help to ensure that the fix is implemented in a way that meets the needs of all stakeholders. Monitor the results. After applying the fix, it is important to monitor the results to make sure that the problem has been resolved and that there are no new problems.

Making changes in production is not ok and can lead to further issues when trying to fix something in an emergency. Panic situations can mean you miss something vital - this is where a staging environment comes in. Staging allows you to "live-test" any fixes and validate them before pushing them to production. CI-CD allows this process to be even smoother and means you can roll your fix from staging into production without any human interaction happening on production systems. If it's 2AM and there is an outage, blurry eyes are not good proof readers and having other team members checking your work is absolutely ok!

Emergency can be a situation where system was overloaded, and you can't even do anything quickly on console. Be ready for a desperate situation like this on your playbook, by including necessary steps to reduce system load (e.g. disabling or limiting some services temporarily) so you can dig deeper and quicker to do assessment.

People who write these things are often not from the real world, where it is production that went down, and nobody knows why yet. There is no "test in non-prod first". What you can do, and should do, is make changes as much as possible, such that they are not permanent, and if you get stuck, you can push the button, and it goes back to how it was with the original problem. It can be hard later to explain to management that you have to go back to the critical system, and change a bunch of things to make it permanent, and reboot to test .. because they are just getting over it being down, but you know this is not as high risk ast the things you had to do to make it work, and it needs to be done this way. Not doing this can be much worse.

After analyzing the incident, the focus shifts to implementing lasting improvements. This involves addressing the root cause by optimizing system design, configuration, and security measures. Automation and scripting can help streamline routine tasks, while monitoring and alerting systems keep a vigilant eye on system health. Regular backups and recovery plans ensure data integrity, while audits enhance overall security. Documentation and configuration files should accurately reflect these changes, and training should be provided to the team and stakeholders to ensure smooth transitions and ongoing maintenance.

Monitor the situation closely and expect problems. During the crisis, you probably created new communication channels (which you documented). Keep those channels open.

I would also recommend the following: # Perform functional and performance tests. Functional tests can help you to confirm that the system is meeting the expected requirements. # Monitor the system for a period of time. Even after the problem has been resolved, it is important to monitor the system for a period of time to make sure that the fix has been effective and that the problem does not recur. # Document the results. Documenting the results of the verification process will help you to track the progress of the incident and to make sure that you do not miss anything important.

Collaborating with the team to implement quick and effective solutions is always a good idea. I also maintain a robust backup and recovery strategy to minimize downtime.

Validating the results can come in many forms. Don't just presume it's worked, check things over! Has the problem stopped? Do the logs look good? Have the monitoring systems stopped screaming at you about the problem? Check everything *you* can and ensure everything is back to as you'd expect it to be. Maybe you have a product or QA team who can test things as well to ensure everything is responding as it should be. Sometimes things can look fine after a fix but maybe a new bug has been introduced that causes unintended consequences which wouldn't cause alerts in the monitoring system (yet) - the people who can test your endpoints, or the process that is used by your customers, can confirm everything is working as it should.

Now is the time for root cause analysis. You may already know, but it's possible you many never find out. Regardless, add what you know to your situation report because you can still draw lessons from it.

I would also recommend the following: # Involve the relevant stakeholders. The people who were involved in the emergency are likely to have valuable insights into the root cause. #Be objective. It is important to be objective when analyzing the cause of the emergency. Avoid blaming individuals or teams, and focus on identifying the root cause of the problem. #Take corrective action. Once you have identified the root cause of the problem, you need to take corrective action to prevent it from recurring. This may involve making changes to the system, the process, or the people involved. #Document the lessons learned. Documenting the lessons learned from the emergency will help you to improve the system and prevent future problems.

Root cause analysis is vital here. Make sure you understand not only what happened, but why. There is no point in assigning blame to people but if it was human error, it's time to review the processes that allowed the problem to arise. Was it a Pull/Merge Request that was blindly approved? Are tests run in your code repository when a PR is created? If so, are they adequate? Is code just pushed to live without proper testing? These are the sorts of questions you should be asking. You should know why it happened and put a plan of action in place with a follow up to ensure the actions are carried out as discussed. Sometimes it's a bug in upstream code and there may be little you can do. Or maybe there is - can you contribute a fix (if FOSS)?

Root cause is hard, because it can be expensive, take time, and you still may never find it. If you have good vendor support, that costs your company money, you will be sending lots of diagnostic information, and they often surprise you with just pure magic, like an unheard of patch. If you are lucky, it was human error from the last change, which hopefully was documented. Sometimes you just have to rebuild the system clean, which defies logic, but almost always works.

Disaster Recovery (DR) is an important thing to have. This can turn hours of downtime into minutes by having somewhere else to flip traffic/workloads to should the worst happen. High availability can allow for some outage too. Regular backups should be taken and restore procedures tested regularly to know the backups are not useless and that people know what to do in an emergency. Work in a least privilege model meaning you should have a little access as possible to any live systems. "Break glass" scenarios do crop up where admin is required but do you need admin all the time? No. Up-to-date documentation on how a system is put together and functions is invaluable. Alerting an monitoring as mentioned in identifying are also invaluable!

Around 2000, the Gartner Group published a study on high availability in which they state that 60% of availability is attributable to your processes and action. The remainder is based on technologies. This underscores the importance of closing the crisis loop with 'lessons learned', which feed system improvements primarily in terms of processes and actions.

Remember to: # The importance of investing in the system. # The need to be proactive in preventing problems. # The importance of communication and collaboration.

See root cause above. Most failures are due to human error, meaning the process can be improved. This turns out to be a mistake in the documentation, or an improvement in the change control. Very few systems go down during super critical "No Changes of any kind allowed" like end of year.

I agree that we as administrators must continue to learn and grow, learn from experience, always be humble, don't forget to share with others.

In this industry the best practices are constantly changing and improving. When I started out we didn't even have DR, just a bunch of servers lashed together. Now we have multi-cloud, multi-region Kubernetes services, it's HA all over the place. There is always the new band-wagon to jump on but you know what? Jump on! Learn it, it could save you millions in money or hours in time spent in a disaster. Being a jack of all trades isn't bad, it gives you a large toolbelt from which you can pull the right tool for the right job and learning all of these processes and tools is priceless. Ask questions, join Slack channels, check StackOverflow and use YouTube to learn. Certifications can help you validate your knowledge and teach you even more.

It is a good practice to set aside a portion of your workday for research. Reading journals, taking courses, and just figuring stuff out. I can't overstate the importance of play for learning. Spend time in the lab. Hypothesize, model, and test.

Continuous learning in Linux admin is essential, utilizing diverse resources, seeking mentorship, and embracing challenges for professional growth and excellence.

During any emergency, effective communication is crucial. You should ensure that you maintain clear and constant communication with your team, stakeholders, and end-users. Provide regular updates on the progress of the resolution and the expected downtime, if any. Transparency and timely updates can help manage expectations and reduce anxiety.

Be open about your mistakes. I once worked with a machinist in Waterloo that said, "The only people who don't make mistakes don't do anything." Senior resources do not butt-cover.

Post analysis documentation is crucial. It helps to provide a base line for any other similar emergency situation that may arise in the future.

Mistakes happen. I've made my fair share over the years and in all cases the world didn't end It's about how you learn from them. I once managed to take down an entire DB at 2:30AM. I was in tmux, syncd-panes and reversed search for a restart command on 3 servers. I thought my last command was to restart the monitoring daemon and so without even reading the command, I smashed enter and bye-bye went the DB... the whole system with a simple restart command. I had to call my DB manager and we sat up until around 6AM lashing everything back together. Lesson - don't sync panes on a prod system! Even earlier in my career I wiped out a customers site with a rm -rf command in the wrong dir. Lesson - don't do that command on customers environments.

Lessons Learned Report When a Linux system administration emergency occurs, it is important to create a comprehensive lessons learned report. This report will document the events of the emergency, the actions taken, and the results of those actions. It will also identify areas where the response could be improved. A lessons learned report can be a valuable resource for future emergencies. It can help to ensure that the same mistakes are not made twice, and that the best practices are followed. It can also help to improve communication and coordination between team members.