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Mastering Apache Cassandra - Second Edition

Book Image

Mastering Apache Cassandra - Second Edition

Overview of this book

Table of Contents (15 chapters)
Mastering Apache Cassandra Second Edition
About the Author
About the Reviewers

Backup and restoration

Cassandra provides a simple backup tool called nodetool snapshot to take incremental snapshots and back up of data. The snapshot command flushes MemTables to the disk and creates a backup by creating a hard link to SSTables (SSTables are immutable).


Hard link is a directory entry associated with file data on a filesystem. It can roughly be assumed as an alias to a file that refers to the location where data is stored. It is unlike a soft link that just aliases filenames, not the actual underlying data.

These hard links stay under the data directory, which is placed under <keyspace>/<column_family>/snapshots.

The general plan to back up a cluster roughly follows these steps:

  1. Take a snapshot of each node one by one. The snapshot command provides an option to specify whether to back up the entire keyspace or just the selected column families.

  2. Taking a snapshot is just half of the story. To be able to restore the database at a later point, you need to move these...