Back up an online database

Remember to plan your backup carefully and to back up each of your databases, including the system database.

Command

A Neo4j database can be backed up in online mode using the backup command of neo4j-admin. The command must be invoked as the neo4j user to ensure the appropriate file permissions.

It is best practice, but not mandatory, to perform the backup from a server on the same network as the database, but that is not part of the cluster. You should install Neo4j on that machine to make the neo4j-admin command available. This machine is known as a backup client.

Neo4j 5 introduces a new version of the backup command which produces immutable backup artifacts (as opposed to mutable folders as in previous versions).

Backup artifact

The neo4j-admin database backup command produces one backup artifact file per database each time it is run. A backup artifact file is an immutable file containing the backup data of a given database along with some metadata like the database name and id, the backup time, the lowest/highest transaction ID, etc.

Backup artifacts can be of two types:

  1. a full backup containing the whole database store or

  2. a differential backup containing a log of transactions to apply to a database store contained in a full backup artifact.

Backup chain

The first time the backup command is run, a full backup artifact is produced for a given database. On the other hand, differential backup artifacts are produced by the subsequent runs.

A backup chain consists of a full backup optionally followed by a sequence of n contiguous differential backups.

backup chain
Figure 1. Backup chain

Usage

The neo4j-admin database backup command can be used for performing an online full or differential backup from a running Neo4j Enterprise server. The produced differential backup artifact contains transaction logs that can be replayed and applied to stores contained in full backup artifacts when restoring a backup chain.

Neo4j’s backup service must have been configured on the server beforehand. The command can be run both locally and remotely. However, it uses a significant amount of resources, such as memory and CPU. Therefore, it is recommended to perform the backup on a separate dedicated machine. The neo4j-admin database backup command also supports SSL/TLS. For more information, see Online backup configurations.

neo4j-admin database backup is not supported in Neo4j Aura.

Syntax

neo4j-admin database backup [-h] [--expand-commands] [--verbose]
                            [--compress[=true|false]] [--keep-failed[=true|false]]
                            [--parallel-recovery[=true|false]]
                            [--additional-config=<file>]
                            [--include-metadata=none|all|users|roles]
                            [--inspect-path=<path>] [--pagecache=<size>]
                            [--to-path=<path>] [--type=<type>]
                            [--from=<host:port>[,<host:port>...]]...
                            [<database>]

Parameters

Table 1. neo4j-admin database backup parameters
Parameter Description Default

<database>

Name of the remote database to backup. Can contain * and ? for globbing (required unless --inspect-path is used).

neo4j

With a single * as a value, you can back up all the databases of the DBMS.

Options

Table 2. neo4j-admin database backup options
Option Description Default

--additional-config=<file>

Configuration file with additional configuration or override the existing configuration settings in the neo4j.conf file.

--compress[=true|false]

Request backup artifact to be compressed. If disabled, backup artifact creation is faster but the size of the produced artifact will be approximately equal to the size of backed-up database.

true

--expand-commands

Allow command expansion in config value evaluation.

--from=<host:port>[,<host:port>…​]

Comma-separated list of host and port of Neo4j instances, each of which are tried in order.

-h, --help

Show this help message and exit.

--include-metadata=none|all|users|roles

Include metadata in file. Can’t be used for backing system database. - roles - commands to create the roles and privileges (for both database and graph) that affect the use of the database - users - commands to create the users that can use the database and their role assignments - all - include roles and users - none - don’t include any metadata

all

--inspect-path=<path>

List and show the metadata of the backup artifact(s). Accepts a folder or a file.

--keep-failed[=true|false]

Request failed backup to be preserved for further post-failure analysis. If enabled, a directory with the failed backup database is preserved.

false

--pagecache=<size>

The size of the page cache to use for the backup process.

--parallel-recovery[=true|false]

Allow multiple threads to apply pulled transactions to a backup in parallel. For some databases and workloads, this may reduce backup times significantly. Note: this is an EXPERIMENTAL option. Consult Neo4j support before use.

false

--to-path=<path>

Directory to place backup in (required unless --inspect-path is used).

--type=<type>

Type of backup to perform. Possible values are: full, diff, and auto. If none is specified, the type is automatically determined based on the existing backups. If you want to force a full backup, use full.

auto

--verbose

Enable verbose output.

Exit codes

Depending on whether the backup was successful or not, neo4j-admin database backup exits with different codes. The error codes include details of what error was encountered.

Table 3. Neo4j Admin backup exit codes when backing up one database
Code Description

0

Success.

1

Backup failed, or succeeded but encountered problems such as some servers being uncontactable. See logs for more details.
Table 4. Neo4j Admin backup exit codes when backing multiple databases
Code Description

0

All databases are backed up successfully.

1

One or several backups failed, or succeeded with problems.

Online backup configurations

Server configuration

The table below lists the basic server parameters relevant to backups. Note that by default, the backup service is enabled but only listens on localhost (127.0.0.1). This needs to be changed if backups are to be taken from another machine.

Table 5. Server parameters for backups
Parameter name Default value Description

server.backup.enabled

true

Enable support for running online backups.

server.backup.listen_address

127.0.0.1:6362

Listening server for online backups.

Memory configuration

The following options are available for configuring the memory allocated to the backup client:

  • Configure heap size for the backup::

HEAP_SIZE configures the maximum heap size allocated for the backup process. This is done by setting the environment variable HEAP_SIZE before starting the operation. If not specified, the Java Virtual Machine chooses a value based on the server resources.

  • Configure page cache for the backup::

The page cache size can be configured by using the --pagecache option of the neo4j-admin database backup command.

You should give the Neo4J page cache as much memory as possible, as long as it satisfies the following constraint:

Neo4J page cache + OS page cache < available RAM, where 2 to 4GB should be dedicated to the operating system’s page cache.

For example, if your current database has a Total mapped size of 128GB as per the debug.log, and you have enough free space (meaning you have left aside 2 to 4 GB for the OS), then you can set --pagecache to 128GB.

Computational resources configurations

Transaction log files

The transaction log files, which keep track of recent changes, are rotated and pruned based on a provided configuration. For example, setting db.tx_log.rotation.retention_policy=3 files keeps 3 transaction log files in the backup. Because recovered servers do not need all of the transaction log files that have already been applied, it is possible to further reduce storage size by reducing the size of the files to the bare minimum. This can be done by setting db.tx_log.rotation.size=1M and db.tx_log.rotation.retention_policy=3 files. You can use the --additional-config parameter to override the configurations in the neo4j.conf file.

Removing transaction logs manually can result in a broken backup.

Security configurations

Securing your backup network communication with an SSL policy and a firewall protects your data from unwanted intrusion and leakage. When using the neo4j-admin database backup command, you can configure the backup server to require SSL/TLS, and the backup client to use a compatible policy. For more information on how to configure SSL in Neo4j, see SSL framework.

Configuration for the backup server should be added to the neo4j.conf file and configuration for backup client to the neo4j-admin.conf file. SSL settings should be set identically between both to ensure compatibility.

The default backup port is 6362, configured with key server.backup.listen_address. The SSL configuration policy has the key of dbms.ssl.policy.backup.

As an example, add the following content to your neo4j.conf and neo4j-admin.conf files:

dbms.ssl.policy.backup.enabled=true
dbms.ssl.policy.backup.tls_versions=TLSv1.2
dbms.ssl.policy.backup.ciphers=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
dbms.ssl.policy.backup.client_auth=REQUIRE

For a detailed list of recommendations regarding security in Neo4j, see Security checklist.

It is very important to ensure that there is no external access to the port specified by the setting server.backup.listen_address. Failing to protect this port may leave a security hole open by which an unauthorized user can make a copy of the database onto a different machine. In production environments, external access to the backup port should be blocked by a firewall.

Cluster configurations

In a cluster topology, it is possible to take a backup from any server hosting the database to backup, and each server has two configurable ports capable of serving a backup. These ports are configured by server.backup.listen_address and server.cluster.listen_address respectively. Functionally, they are equivalent for backups, but separating them can allow some operational flexibility, while using just a single port can simplify the configuration. It is generally recommended to select secondary servers to act as backup servers since they are more numerous than primary servers in typical cluster deployments. Furthermore, the possibility of performance issues on a secondary server, caused by a large backup, does not affect the performance or redundancy of the primary servers. If a secondary server is not available, then a primary can be selected based on factors, such as its physical proximity, bandwidth, performance, and liveness.

Use the SHOW DATABASES command to learn which database is hosted on which server.

To avoid taking a backup from a cluster member that is lagging behind, you can look at the transaction IDs by exposing Neo4j metrics or via Neo4j Browser. To view the latest processed transaction IDs (and other metrics) in Neo4j Browser, type :sysinfo at the prompt.

Targeting multiple servers

It is recommended to provide a list of multiple target servers when taking a backup from a cluster, since that may allow a backup to succeed even if some server is down, or not all databases are hosted on the same servers. If the command finds one or more servers that do not respond, it continues trying to backup from other servers and continues backing up other requested databases, but the exit code of the command is non-zero, to alert the user to the fact there is a problem. If a name pattern is used for the database together with multiple target servers, all servers contribute to the list of matching databases.

Examples

The following are examples of how to perform a backup of a single database and multiple databases. The target directory /mnt/backups/neo4j must exist before calling the command and the database(s) must be online.

Example 1. Perform a backup of a single database

You do not need to use the --type option to specify the type of backup. By default, the type is automatically determined based on the existing backups.

bin/neo4j-admin database backup --to-path=/path/to/backups/neo4j neo4j
Example 2. Perform a forced full backup of a single database.

If you want to force a full backup after several differential backups, you can use the --type=full option.

bin/neo4j-admin database backup --type=full --to-path=/path/to/backups/neo4j neo4j
Example 3. Use neo4j-admin database backup to back up multiple databases.

To back up several databases that match database a pattern you can use name globbing. For example, to backup all databases that start with n from your three-node cluster, run:

neo4j-admin database backup --from=192.168.1.34:6362,192.168.1.35:6362,192.168.1.36:6362 --to-path=/mnt/backups/neo4j --pagecache=4G "n*"