There are risks involved with using a Single-AZ, such as large downtimes which could disrupt business operations. Single-AZ setups should only be used for your database instances if your RTO (Recovery Time Objective) and RPO (Recovery Point Objective) are high enough to allow for it. When the failover is complete, it can also take additional time for the RDS Console (UI) to reflect the new Availability Zone. They can be longer though, as large transactions or a lengthy recovery process can increase failover time. Failover times depend on the completion of the setup which is often based on the size and activity of the database as well as other conditions present at the time the primary DB instance became unavailable.įailover times are typically 60-120 seconds. These AZ’s are highly-available, state-of-the-art facilities protecting your database instances. This AZ is typically in another branch of the data center, often far from the current availability zone where instances are located. When catastrophe or disaster occurs, such as unplanned outages or natural disasters where your database instances are affected, Amazon RDS automatically switches to a standby replica in another Availability Zone. Let’s check each of them on how does failover being processed. When deploying your Amazon RDS nodes, you can setup your database cluster with Multi-Availability Zone (AZ) or to a Single-Availability Zone. How Does Amazon RDS Handle Database Failover? Since we are dealing with Amazon RDS, there’s really no need for you to be overly concerned about these type of issues since it’s a managed service with most jobs being handled by Amazon. Its main objective is to simply bring back the good, old master to the latest state and restore the replication setup to its original topology. This approach provides your engineers enough time to plan carefully and rehearse the exercise to ensure a smooth transition. This situation might be okay temporarily, but in the long run, the designated master must be brought back to lead the replication after it is deemed healthy (or maintenance is completed).Ĭontrary to failover, failback operations usually happen in a controlled environment by using switchover. When failover is required during disaster recovery (or for maintenance) it’s not uncommon that when promoting a new master you might use inferior hardware. Your master setup requires adequate hardware specs to ensure it can process writes, generate replication events, process critical reads, etc, in a stable way. In a typical replicated environment the master must be powerful enough to carry a huge load, especially when the workload requirement is high. In the previous blog we also covered why you would need to failback. We’ll talk about that later in this blog. This service manages things such as hardware issues, backup and recovery, software updates, storage upgrades, and even software patching. In Amazon RDS you don’t need to do this, nor are you required to monitor it yourself, as RDS is a managed database service (meaning Amazon handles the job for you). Failover switches it to a stable state of redundancy or to a standby computer server, system, hardware component, or network. As discussed in a previous blog the need to failover occurs once your current database master experiences a network failure or abnormal termination of the host system. Database Failover in Amazon RDSįailover occurs automatically (as manual failover is called switchover). If you are concerned about how your system would perform when responding to your system’s Fault Detection, Isolation, and Recovery (FDIR), then failover and failback should be of high importance. Why You Would Need to Failover or Failback?ĭesigning a large system that is fault-tolerant, highly-available, with no Single-Point-Of-Failure (SPOF) requires proper testing to determine how it would react when things go wrong. Aurora is part of the managed database service Amazon RDS, a web service that makes it easy to set up, operate, and scale a relational database in the cloud. For those not familiar with Aurora, it is a fully managed relational database engine that’s compatible with MySQL and PostgreSQL. When comparing the tech-giant public clouds which supports managed relational database services, Amazon is the only one that offers an alternative option (along with MySQL/MariaDB, PostgreSQL, Oracle, and SQL Server) to deliver its own kind of database management called Amazon Aurora. We will also look at how you can perform a failback of your former master node, bringing it back to its original order as a master. Previously we posted a blog discussing Achieving MySQL Failover & Failback on Google Cloud Platform (GCP) and in this blog we’ll look at how it’s rival, Amazon Relational Database Service (RDS), handles failover.
0 Comments
Leave a Reply. |