About Database Journaling

NuoDB's architecture consists of interactive processes that operate over three layers: a management tier (brokers, agents), a storage tier (storage managers) and a transaction tier (transaction engines).

The storage tier is responsible for maintaining a complete copy of the database. The atomThe internal object structure representing all data in a NuoDB database. Atoms are self-coordinating objects that represent specific types of information (such as data, indexes or schemas).s, or database elements, are persisted by the archive storage (e.g., disk, S3, HDFS). Data can be stored locally or in the cloud. Atoms are written by a specific storage manager module called the archive. The journal is used to write all messages from the transaction engines. These messages are subsequently applied to the database elements by the storage manager and persisted to the archive. Journaled messages are important because they can be used to recover data lost by an SM unexpected termination, process kill, or power loss.

If journaling is enabled, you can use database options to:

See the following topics:

Data Loss If Journaling is Not Happening

How Journaling Ensures Data Recovery