Today we are sharing a lesson from ScyllaDB University. At the bottom we provide a link to the hands-on lab. ScyllaDB University is a fully free service provided by ScyllaDB to foster the NoSQL database community; all readers are welcome to register to take this and other available courses.
This lesson deals with what repair is and why it is needed for tombstones, why it is important, and ScyllaDB Manager.
ScyllaDB Manager is a centralized cluster administration and recurrent tasks automation tool. ScyllaDB Manager can schedule tasks such as repairs and backups.
ScyllaDB Repair is a process that runs in the background and synchronizes the data between nodes so that eventually, all the replicas hold the same data. Data stored on nodes can become inconsistent with other replicas over time, which is why repairs are a necessary part of database maintenance. Using ScyllaDB repair makes data on the node consistent with the other nodes in the cluster. The best use of ScyllaDB repair is to have the ScyllaDB Manager schedule and run the repairs for you.
You can also learn more about ScyllaDB Manager here.
Repairs
In this lesson you’ll learn about repair and why is it needed. A common misconception is that repairs are a way to fix “things” that are wrong with the database.
So what are repairs? ScyllaDB Repair is a process that runs in the background and synchronizes the data between nodes so that eventually, all the replicas hold the same data. Data stored on nodes can become inconsistent with other replicas over time, which is why repairs are a necessary part of database maintenance. Using ScyllaDB repair makes data on the node consistent with the other nodes in the cluster.
What are tombstones and why are they important?
Data written to ScyllaDB gets persisted to SSTables. Since SSTables are immutable, the data can’t actually be removed when a delete is performed, instead, a marker (also called a “tombstone”) is written to indicate the value’s new status. When compaction occurs, the data will be expunged completely and the corresponding disk space recovered.
Manager Overview
An overview of ScyllaDB Manager, what is it, and how it can be used to improve cluster management. ScyllaDB Manager is a centralized cluster administration and recurrent tasks automation tool. It can be used to schedule tasks such as repairs and backups.
Notice that since Manager 2.0 has been released, ScyllaDB Manager does not use SSH to directly communicate with the node, rather it uses the Manager Agent. Learn more about it here.
ScyllaDB Manager Deep Dive
In this lesson you’ll learn about ScyllaDB cluster management and administration. It covers the ScyllaDB Manager: an overview, configuration, deployment, health check, adding a cluster, and more.
ScyllaDB Manager 2.0: What’s New, Agent and Rclone
An Overview of changes in ScyllaDB Manager 2.0, it’s new features and capabilities, and how to use it. ScyllaDB Manager is a tool used to manage a ScyllaDB cluster. Some of its capabilities include repair, backup, and maintenance.
Backup and Restore
A deep dive into backup, how it’s performed, its benefits, and a CLI example of running it.
Take the Hands-on Lab!
After reviewing all of the videos above, ScyllaDB University then has an online Monitoring and Manager Lab. Make sure you take it to get some hands-on experience, and also so that ScyllaDB University can track your learning progress.
