> ## Documentation Index
> Fetch the complete documentation index at: https://clickhouse.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# backup_restore_* session settings

> ClickHouse session settings in the backup_restore_* generated group.

export const SettingsInfoBlock = ({type, default_value, changeable_without_restart}) => {
  return <div className="not-prose" style={{
    display: "flex",
    flexWrap: "wrap",
    alignItems: "baseline",
    columnGap: "0.5rem",
    rowGap: "0.125rem",
    margin: "0.375rem 0",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <div style={{
    fontWeight: 600,
    opacity: 0.72
  }}>Type</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>Default</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          Changeable without restart
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

These settings are available in [system.settings](/docs/reference/system-tables/settings) and are autogenerated from [source](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp).

<h2 id="backup_restore_batch_size_for_keeper_multi">
  backup\_restore\_batch\_size\_for\_keeper\_multi
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

Maximum size of batch for multi request to \[Zoo]Keeper during backup or restore

<h2 id="backup_restore_batch_size_for_keeper_multiread">
  backup\_restore\_batch\_size\_for\_keeper\_multiread
</h2>

<SettingsInfoBlock type="UInt64" default_value="10000" />

Maximum size of batch for multiread request to \[Zoo]Keeper during backup or restore

<h2 id="backup_restore_failure_after_host_disconnected_for_seconds">
  backup\_restore\_failure\_after\_host\_disconnected\_for\_seconds
</h2>

<SettingsInfoBlock type="UInt64" default_value="3600" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "3600"},{"label": "New setting."}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "3600"},{"label": "New setting."}]}]} />

If a host during a BACKUP ON CLUSTER or RESTORE ON CLUSTER operation doesn't recreate its ephemeral 'alive' node in ZooKeeper for this amount of time then the whole backup or restore is considered as failed.
This value should be bigger than any reasonable time for a host to reconnect to ZooKeeper after a failure.
Zero means unlimited.

<h2 id="backup_restore_finish_timeout_after_error_sec">
  backup\_restore\_finish\_timeout\_after\_error\_sec
</h2>

<SettingsInfoBlock type="UInt64" default_value="180" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "180"},{"label": "New setting."}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "180"},{"label": "New setting."}]}]} />

How long the initiator should wait for other host to react to the 'error' node and stop their work on the current BACKUP ON CLUSTER or RESTORE ON CLUSTER operation.

<h2 id="backup_restore_keeper_fault_injection_probability">
  backup\_restore\_keeper\_fault\_injection\_probability
</h2>

<SettingsInfoBlock type="Float" default_value="0" />

Approximate probability of failure for a keeper request during backup or restore. Valid value is in interval \[0.0f, 1.0f]

<h2 id="backup_restore_keeper_fault_injection_seed">
  backup\_restore\_keeper\_fault\_injection\_seed
</h2>

<SettingsInfoBlock type="UInt64" default_value="0" />

0 - random seed, otherwise the setting value

<h2 id="backup_restore_keeper_max_retries">
  backup\_restore\_keeper\_max\_retries
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "1000"},{"label": "Should be big enough so the whole operation BACKUP or RESTORE operation won't fail because of a temporary [Zoo]Keeper failure in the middle of it."}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "1000"},{"label": "Should be big enough so the whole operation BACKUP or RESTORE operation won't fail because of a temporary [Zoo]Keeper failure in the middle of it."}]}]} />

Max retries for \[Zoo]Keeper operations in the middle of a BACKUP or RESTORE operation.
Should be big enough so the whole operation won't fail because of a temporary \[Zoo]Keeper failure.

<h2 id="backup_restore_keeper_max_retries_while_handling_error">
  backup\_restore\_keeper\_max\_retries\_while\_handling\_error
</h2>

<SettingsInfoBlock type="UInt64" default_value="20" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "20"},{"label": "New setting."}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "20"},{"label": "New setting."}]}]} />

Max retries for \[Zoo]Keeper operations while handling an error of a BACKUP ON CLUSTER or RESTORE ON CLUSTER operation.

<h2 id="backup_restore_keeper_max_retries_while_initializing">
  backup\_restore\_keeper\_max\_retries\_while\_initializing
</h2>

<SettingsInfoBlock type="UInt64" default_value="20" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.11"},{"label": "20"},{"label": "New setting."}]}, {"id": "row-2","items": [{"label": "24.10"},{"label": "20"},{"label": "New setting."}]}]} />

Max retries for \[Zoo]Keeper operations during the initialization of a BACKUP ON CLUSTER or RESTORE ON CLUSTER operation.

<h2 id="backup_restore_keeper_retry_initial_backoff_ms">
  backup\_restore\_keeper\_retry\_initial\_backoff\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="100" />

Initial backoff timeout for \[Zoo]Keeper operations during backup or restore

<h2 id="backup_restore_keeper_retry_max_backoff_ms">
  backup\_restore\_keeper\_retry\_max\_backoff\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="5000" />

Max backoff timeout for \[Zoo]Keeper operations during backup or restore

Cloud default value: `60000`.

<h2 id="backup_restore_keeper_value_max_size">
  backup\_restore\_keeper\_value\_max\_size
</h2>

<SettingsInfoBlock type="UInt64" default_value="1048576" />

Maximum size of data of a \[Zoo]Keeper's node during backup

<h2 id="backup_restore_s3_retry_attempts">
  backup\_restore\_s3\_retry\_attempts
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.7"},{"label": "1000"},{"label": "Setting for Aws::Client::RetryStrategy, Aws::Client does retries itself, 0 means no retries. It takes place only for backup\/restore."}]}]} />

Setting for Aws::Client::RetryStrategy, Aws::Client does retries itself, 0 means no retries. It takes place only for backup/restore.

<h2 id="backup_restore_s3_retry_initial_backoff_ms">
  backup\_restore\_s3\_retry\_initial\_backoff\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="25" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "25"},{"label": "New setting"}]}]} />

Initial backoff delay in milliseconds before the first retry attempt during backup and restore. Each subsequent retry increases the delay exponentially, up to the maximum specified by `backup_restore_s3_retry_max_backoff_ms`

<h2 id="backup_restore_s3_retry_jitter_factor">
  backup\_restore\_s3\_retry\_jitter\_factor
</h2>

<SettingsInfoBlock type="Float" default_value="0.1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "0.1"},{"label": "New setting"}]}]} />

Jitter factor applied to the retry backoff delay in Aws::Client::RetryStrategy during backup and restore operations. The computed backoff delay is multiplied by a random factor in the range \[1.0, 1.0 + jitter], up to the maximum `backup_restore_s3_retry_max_backoff_ms`. Must be in \[0.0, 1.0] interval

<h2 id="backup_restore_s3_retry_max_backoff_ms">
  backup\_restore\_s3\_retry\_max\_backoff\_ms
</h2>

<SettingsInfoBlock type="UInt64" default_value="5000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.8"},{"label": "5000"},{"label": "New setting"}]}]} />

Maximum delay in milliseconds between retries during backup and restore operations.