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MySQL 8.0 Reference Manual  / ...  / MySQL NDB Cluster 8.0  / Management of NDB Cluster  / Online Backup of NDB Cluster  /  Using The NDB Cluster Management Client to Create a Backup

25.6.8.2 Using The NDB Cluster Management Client to Create a Backup

Before starting a backup, make sure that the cluster is properly configured for performing one. (SeeSection 25.6.8.3, “Configuration for NDB Cluster Backups”.)

TheSTART BACKUP command is used to create a backup, and has the syntax shown here:

START BACKUP [backup_id]    [encryption_option]    [wait_option]    [snapshot_option]encryption_option:ENCRYPT [PASSWORD=password]password:{'password_string' | "password_string"}wait_option:WAIT {STARTED | COMPLETED} | NOWAITsnapshot_option:SNAPSHOTSTART | SNAPSHOTEND

Successive backups are automatically identified sequentially, so thebackup_id, an integer greater than or equal to 1, is optional; if it is omitted, the next available value is used. If an existingbackup_id value is used, the backup fails with the errorBackup failed: file already exists. If used, thebackup_id must follow immediately after theSTART BACKUP keywords, before any other options are used.

In NDB 8.0.22 and later,START BACKUP supports the creation of encrypted backups usingENCRYPT PASSWORD=password. Thepassword must meet all of the following requirements:

  • Uses any of the printable ASCII characters except!,',",$,%,\, and^

  • Is no more than 256 characters in length

  • Is enclosed by single or double quotation marks

WhenENCRYPT PASSWORD='password' is used, the backup data record and log files written by each data node are encrypted with a key derived from the user-providedpassword and a randomly-generated salt using a key derivation function (KDF) that employs the PBKDF2-SHA256 algorithm to generate a symmetric encryption key for that file. This function has the form shown here:

key = KDF(random_salt,password)

The key so generated is then used to encrypt the backup data using AES 256 CBC inline, and symmetric encryption is employed for encrypting the backup fileset (with the generated key).

Note

NDB Clusternever saves the user-furnished password or generated encryption key.

Starting with NDB 8.0.24, thePASSWORD option can be omitted fromencryption_option. In this case, the management client prompts the user for a password.

It is possible usingPASSWORD to set an empty password ('' or""), but this is not recommended.

An encrypted backup can be decrypted using any of the following commands:

NDB 8.0.24 and later supports the additional commands listed here:

See the descriptions of these programs for more information, such as additional options that may be required.

Thewait_option can be used to determine when control is returned to the management client after aSTART BACKUP command is issued, as shown in the following list:

  • IfNOWAIT is specified, the management client displays a prompt immediately, as seen here:

    ndb_mgm> START BACKUP NOWAITndb_mgm>

    In this case, the management client can be used even while it prints progress information from the backup process.

  • WithWAIT STARTED the management client waits until the backup has started before returning control to the user, as shown here:

    ndb_mgm> START BACKUP WAIT STARTEDWaiting for started, this may take several minutesNode 2: Backup 3 started from node 1ndb_mgm>

  • WAIT COMPLETED causes the management client to wait until the backup process is complete before returning control to the user.

WAIT COMPLETED is the default.

Asnapshot_option can be used to determine whether the backup matches the state of the cluster whenSTART BACKUP was issued, or when it was completed.SNAPSHOTSTART causes the backup to match the state of the cluster when the backup began;SNAPSHOTEND causes the backup to reflect the state of the cluster when the backup was finished.SNAPSHOTEND is the default, and matches the behavior found in previous NDB Cluster releases.

Note

If you use theSNAPSHOTSTART option withSTART BACKUP, and theCompressedBackup parameter is enabled, only the data and control files are compressed—the log file is not compressed.

If both await_option and asnapshot_option are used, they may be specified in either order. For example, all of the following commands are valid, assuming that there is no existing backup having 4 as its ID:

START BACKUP WAIT STARTED SNAPSHOTSTARTSTART BACKUP SNAPSHOTSTART WAIT STARTEDSTART BACKUP 4 WAIT COMPLETED SNAPSHOTSTARTSTART BACKUP SNAPSHOTEND WAIT COMPLETEDSTART BACKUP 4 NOWAIT SNAPSHOTSTART

The procedure for creating a backup consists of the following steps:

  1. Start the management client (ndb_mgm), if it not running already.

  2. Execute theSTART BACKUP command. This produces several lines of output indicating the progress of the backup, as shown here:

    ndb_mgm> START BACKUPWaiting for completed, this may take several minutesNode 2: Backup 1 started from node 1Node 2: Backup 1 started from node 1 completed StartGCP: 177 StopGCP: 180 #Records: 7362 #LogRecords: 0 Data: 453648 bytes Log: 0 bytesndb_mgm>

  3. When the backup has started the management client displays this message:

    Backupbackup_id started from nodenode_id

    backup_id is the unique identifier for this particular backup. This identifier is saved in the cluster log, if it has not been configured otherwise.node_id is the identifier of the management server that is coordinating the backup with the data nodes. At this point in the backup process the cluster has received and processed the backup request. It does not mean that the backup has finished. An example of this statement is shown here:

    Node 2: Backup 1 started from node 1

  4. The management client indicates with a message like this one that the backup has started:

    Backupbackup_id started from nodenode_id completed

    As is the case for the notification that the backup has started,backup_id is the unique identifier for this particular backup, andnode_id is the node ID of the management server that is coordinating the backup with the data nodes. This output is accompanied by additional information including relevant global checkpoints, the number of records backed up, and the size of the data, as shown here:

    Node 2: Backup 1 started from node 1 completed StartGCP: 177 StopGCP: 180 #Records: 7362 #LogRecords: 0 Data: 453648 bytes Log: 0 bytes

It is also possible to perform a backup from the system shell by invokingndb_mgm with the-e or--execute option, as shown in this example:

$> ndb_mgm -e "START BACKUP 6 WAIT COMPLETED SNAPSHOTSTART"

When usingSTART BACKUP in this way, you must specify the backup ID.

Cluster backups are created by default in theBACKUP subdirectory of theDataDir on each data node. This can be overridden for one or more data nodes individually, or for all cluster data nodes in theconfig.ini file using theBackupDataDir configuration parameter. The backup files created for a backup with a givenbackup_id are stored in a subdirectory namedBACKUP-backup_id in the backup directory.

Cancelling backups.  To cancel or abort a backup that is already in progress, perform the following steps:

  1. Start the management client.

  2. Execute this command:

    ndb_mgm> ABORT BACKUPbackup_id

    The numberbackup_id is the identifier of the backup that was included in the response of the management client when the backup was started (in the messageBackupbackup_id started from nodemanagement_node_id).

  3. The management client acknowledges the abort request withAbort of backupbackup_id ordered.

    Note

    At this point, the management client has not yet received a response from the cluster data nodes to this request, and the backup has not yet actually been aborted.

  4. After the backup has been aborted, the management client reports this fact in a manner similar to what is shown here:

    Node 1: Backup 3 started from 5 has been aborted.  Error: 1321 - Backup aborted by user request: Permanent error: User defined errorNode 3: Backup 3 started from 5 has been aborted.  Error: 1323 - 1323: Permanent error: Internal errorNode 2: Backup 3 started from 5 has been aborted.  Error: 1323 - 1323: Permanent error: Internal errorNode 4: Backup 3 started from 5 has been aborted.  Error: 1323 - 1323: Permanent error: Internal error

    In this example, we have shown sample output for a cluster with 4 data nodes, where the sequence number of the backup to be aborted is3, and the management node to which the cluster management client is connected has the node ID5. The first node to complete its part in aborting the backup reports that the reason for the abort was due to a request by the user. (The remaining nodes report that the backup was aborted due to an unspecified internal error.)

    Note

    There is no guarantee that the cluster nodes respond to anABORT BACKUP command in any particular order.

    TheBackupbackup_id started from nodemanagement_node_id has been aborted messages mean that the backup has been terminated and that all files relating to this backup have been removed from the cluster file system.

It is also possible to abort a backup in progress from a system shell using this command:

$> ndb_mgm -e "ABORT BACKUPbackup_id"
Note

If there is no backup having the IDbackup_id running when anABORT BACKUP is issued, the management client makes no response, nor is it indicated in the cluster log that an invalid abort command was sent.