# Transaction Logs and Snapshots

Each partition on a node has a set of transaction logs that contain database updates made by [DDL](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-definition-language-ddl.md) and [DML](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-manipulation-language-dml.md) commands. A snapshot is a database backup that contains only the in-memory rowstore data (of committed transactions). A snapshot is triggered each time the size of transaction logs reaches a predefined threshold. Snapshots can also be triggered manually for individual databases.

Transaction logs that are committed to snapshots are truncated to save disk space. In addition, old snapshots can be periodically deleted by configuring engine variables. At any given point, only transaction logs that are currently used by snapshots are stored on the disk.

Note that transaction logs are not stored in a human-readable format, unlike [query log](https://docs.singlestore.com/db/v9.1/reference/troubleshooting-reference/trace-log/logging-queries.md) that is a text file.

The following sections provide general information about transaction logs and snapshots and further explain how to configure and manage the disk space used by them.

## In this section

* [How Snapshots and Logs are Used](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/usage.md)
* [Replay Configuration](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/replay-configuration.md)
* [Storage Location for Transaction Logs and Snapshots](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/storage-location.md)
* [Configuring Transaction Logs and Snapshots](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/configure.md)
* [Managing Disk Space Used by Transaction Logs](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/manage-disk-space.md)
* [Error Handling](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/errors.md)

***

Modified at: November 17, 2022

Source: [/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/transaction-logs-snapshots/)

(An index of the documentation is available at /llms.txt)