Self Healing

• Linked to availability

• Self-healing is a property going beyond graceful failure handling; it is the ability to detect and fix problems automatically without human intervention

  • difficult and costly to build

  • Minimizing the mean time to recovery and automating the repair process is what self-healing is all about.

    -

• you want to make your system appear as if all of its components were functioning perfectly even when things break and during maintenance times.

  • so in times of failures, system should still be functioning

• As you scale out, failures become a much more frequent occurrence.

• Be able to handle power outages, human error, network failures

• Always prepare for these failures

• Trigger them yourselves and to test your self healing, responsiveness etc

  • chaos monkey

• Crash-Only

  • the system should always be ready to crash, and whenever it reboots, it should be able to continue to work without human interaction

  • he system needs to be able to detect its failure, fix the broken data if necessary, and start work as normal,

  • if you want to shut the system down, you need to terminate it

• ensuring high availability is mainly about removing single points of failure and graceful failover.

  • Single point of failure is any piece of infrastructure that is necessary for the system to work properly

  • Once you identify your single points of failure, you need to decide with your business team whether it is a good investment to put redundancy in place.

    • Redundancy is having more than one copy of each piece of data or each component of the infrastructure

    • Systems that are not redundant need special attention, and it is a best practice to prepare a disaster recovery plan (sometimes called a business continuity plan) with recovery procedures for all critical pieces of infrastructure.