How to create a backup

While running, Memgraph generates several different files in its data directory. This is the location where Memgraph saves all permanent data. The default data directory is /var/lib/memgraph and you can change it in the main Memgraph configuration file.

The data directory includes multiple different subdirectories, one of them being the storage directory, which contains the durability files. In that directory, Memgraph periodically generates snapshots and WAL files that contain Memgraph's data in a recoverable format.

Snapshot is created periodically based on the time defined with the --storage-snapshot-interval-sec config in the Memgraph configuration file.

1. Creating a snapshot

If you want to trigger creating a snapshot of the current database state, run the following query in mgconsole or Memgraph Lab:

CREATE SNAPSHOT;

2. Locking the data directory

Creating a backup of a Memgraph instance would consist of simply copying the data directory. This is impossible without additional help because the durability files can be deleted when an event is triggered (the number of snapshots exceeded the maximum allowed number).

To disable this behavior, you can use the following query in mgconsole or Memgraph Lab:

LOCK DATA DIRECTORY;

3. Copying data directory and unlocking

The deletion of every file contained in the data directory is delayed until you unlock it again. You can safely copy the data directory or a single snapshot to another location without worrying that it will be deleted during copying.

Copy files if you are using Memgraph on Linux

If you are using Linux to run Memgraph, here are the steps for copying files:

1. Start your Memgraph instance.

2. Open a new Linux terminal and check the location of the permanent data directory:

grep -A 1 'permanent data' /etc/memgraph/memgraph.conf

If you are getting a permission error, execute the sudo su command to get access privileges and then try to change the working directory again.

Your output should look something like this:

# Path to directory in which to save all permanent data. [string]
--data-directory=/var/lib/memgraph

As you can see, the path is the default one: /var/lib/memgraph.

3. Locate the files that you want to backup. Let's say that you want to copy the latest snapshot, list the content of the snapshot directory and then copy the latest file.

ls -l /var/lib/memgraph/snapshots/

total 35920
-rw-r----- 1 memgraph memgraph  7185673 Mar 25 13:52 20220325125206991975_timestamp_2622
-rw-r----- 1 memgraph memgraph 12521724 Mar 25 13:52 20220325125237040637_timestamp_3028
-rw-r----- 1 memgraph memgraph 17064381 Mar 25 13:53 20220325125308366007_timestamp_3380

4. Copy a file from the snapshot directory to the backup folder:

cp /var/lib/memgraph/snapshots/20220325125308366007_timestamp_3380 ~/backup/

To allow the deletion of the files, run the following query in mgconsole or Memgraph Lab::

UNLOCK DATA DIRECTORY;

Memgraph will delete the files which should have been deleted before and allow any future deletion of the files contained in the data directory.