backups_* server settings - ClickHouse Documentation

These settings configure the ClickHouse server and are autogenerated from ClickHouse source.

backups

Settings for backups, used when executing the BACKUP and RESTORE statements. The following settings can be configured by sub-tags:

Setting	Type	Description	Default
`allow_concurrent_backups`	Bool	Determines whether multiple backup operations can run concurrently on the same host.	`true`
`allow_concurrent_restores`	Bool	Determines whether multiple restore operations can run concurrently on the same host.	`true`
`allowed_disk`	String	Disk to backup to when using `File()`. This setting must be set in order to use `File`.	“
`allowed_path`	String	Path to backup to when using `File()`. This setting must be set in order to use `File`.	“
`attempts_to_collect_metadata_before_sleep`	UInt	Number of attempts to collect metadata before sleeping in case of inconsistency after comparing collected metadata.	`2`
`collect_metadata_timeout`	UInt64	Timeout in milliseconds for collecting metadata during backup.	`600000`
`compare_collected_metadata`	Bool	If true, compares the collected metadata with the existing metadata to ensure they are not changed during backup .	`true`
`create_table_timeout`	UInt64	Timeout in milliseconds for creating tables during restore.	`300000`
`max_attempts_after_bad_version`	UInt64	Maximum number of attempts to retry after encountering a bad version error during coordinated backup/restore.	`3`
`max_sleep_before_next_attempt_to_collect_metadata`	UInt64	Maximum sleep time in milliseconds before the next attempt to collect metadata.	`100`
`min_sleep_before_next_attempt_to_collect_metadata`	UInt64	Minimum sleep time in milliseconds before the next attempt to collect metadata.	`5000`
`remove_backup_files_after_failure`	Bool	If the `BACKUP` command fails, ClickHouse will try to remove the files already copied to the backup before the failure, otherwise it will leave the copied files as they are.	`true`
`sync_period_ms`	UInt64	Synchronization period in milliseconds for coordinated backup/restore.	`5000`
`test_inject_sleep`	Bool	Testing related sleep	`false`
`test_randomize_order`	Bool	If true, randomizes the order of certain operations for testing purposes.	`false`
`zookeeper_path`	String	Path in ZooKeeper where backup and restore metadata is stored when using `ON CLUSTER` clause.	`/clickhouse/backups`

This setting is configured by default as:

<backups>
    ....
</backups>

backups_io_thread_pool_queue_size

The maximum number of jobs that can be scheduled on the Backups IO Thread pool. It is recommended to keep this queue unlimited due to the current S3 backup logic.

A value of 0 (default) means unlimited.

Last modified on July 22, 2026