How to backup a CCN

The data stored by aleph.im Core Channel Nodes (CRN) is redundant and can be retrieved from the network in case of emergencies. However, there are a few important factors to consider in order to minimize node downtime, safeguard reputation, and maximize rewards.

What to back up

Secret Keys

The first essential step is to backup the keys used in the P2P protocol by the Core Channel Node.

These keys are located in the pyaleph/keys/* directory. It is sufficient to perform this backup only once, as these keys will not change.

⚠️ Reinstalling a node with the same IPv4 will fail if these keys change, as other nodes will only trust the same key for a duration of many hours or days.

File Storage

The second aspect you may consider backing up is the file storage. If you are using the provided docker-compose.yml file, the file storage is located in the Docker volume named pyaleph-ipfs. It is acceptable to have an incomplete backup, as it enables faster resynchronization from the network by eliminating the need to download those files again.

PostgreSQL Database

Additionally, it is recommended to backup the PostgreSQL database stored in the Docker volume pyaleph-postgres. When restoring your node, ensure that the file storage mentioned above is not older than this database volume.

Full resynchronisation

Performing backups of the file storage and the PostgreSQL database will enable faster node recovery compared to downloading and processing all messages from the network. However, keep in mind that there is always a possibility of relying solely on network synchronization.

Tooling

The choice of backup solution depends on your specific installation.

Filesystem snapshots

A popular approach is to install run the Docker volumes on the BTRFS or ZFS filesystem and utilizing the snapshots provided by those file systems. Others prefer running Core Channel Nodes in virtual machines and utilizing the snapshot features of the QCOW image format.

Backup tools

An alternative using regular tools is to use the following commands:

Database

Backup:

docker exec -t pyaleph_postgres_1 pg_dumpall -c -U postgres > dump_`date +%d-%m-%Y"_"%H_%M_%S`.sql

Restore:

cat your_dump.sql | docker exec -i pyaleph_postgres_1 psql -U postgres

File storage

Backup:

rsync -av /var/lib/docker/volumes/pyaleph_pyaleph-local-storage/ user@your-backup-server:/path/to/directory

Restore (untested):

rsync -av user@your-backup-server:/path/to/directory /var/lib/docker/volumes/pyaleph_pyaleph-local-storage/